This guide assumes that you are new to the game and that you want to tackle the Invasion campaign on the highest difficulty - Legend - but is meant to be useful for all newbies so I go into a bit more detail than is absolutely necessary. The guide explains the main game mechanics, focuses on how (and why) to build up your army & your heroes and gives some advice on the levels with difficulty spikes.

Spoilers are avoided as much as possible. There are no story related spoilers. Info on which units you can add to your army is kept vague or dropped completely where possible. There are no spoilers on the type of enemies you encounter except for 1.5 specific units that you need to be aware of before you start your campaign. I decided to refrain from posting screenshots altogether to avoid spoilers. I tried to be spoiler-free in my section about the hardest missions as well but you want to skip those if you want to go in blind.

By adhering to the army composition discussed here you will finish maps in the second half of the game (the last third at the latest) in approximately 15 out of your 40-odd turns (on Legend difficulty). The last two maps took me 15 and 9 turns respectively (conquering all loot locations and killing all enemy units) without going for speed and on my first try. You will probably do even better than that. Obviously, you will not be taking any significant damage - that would slow you down and would be in poor style.

This guide turned out quite a bit longer than planned (it is a complex game after all) but the TL;DR gives you all you need to know to get started and most sections can be skipped or read on their own.

Our strategy is to kill everything in one turn and route what cannot be killed. The turn after the slaughter we move on towards our objectives and kill stragglers while our wolves get the army back together.

We need to be able to insta-kill groups of about 3 units in early game, battlegroups of about 6-9 units in mid game and armies of 12-20 units in late game. All of which is doable (most of the time).

Before we discuss how the game works and which units to choose: here is the summary / TL;DR on what to do. If you are playing on a more lenient difficulty this is all you need.

You ALWAYS want to leave 1 supply unused and search camps to grab imperial volunteers to get Fire Archers. You cannot have enough Fire Archers (well, 8 of them would be a good goal). If you are maxing out your supply you transition from Slingers to more Fire Archers. Read: sell a Slinger.

In early game you want to grab:

• 1 Berserker. (You can postpone the upgrade to Cleavers.)
  
• 3 Slingers. (You can skip the upgrade to Wolf Hunters and hopefully the one to Thunderers as well)
  
• 2-3 Stag Lancers. (For magic damage and range.)
  
• 1 Wolf Mother. (Using your first liquid mana.)
  
• 0+ Imperial Volunteers. (As many as possible; to be upgraded to Longbowmen asap.)
  
• 0+ Spear Maidens. (You start with a named unit of maidens. If you want to retain 0 cavalry after mid game but want to keep the named unit for lore reasons you want to upgrade her to a Spear Maiden. Do so before "Thieves in the night". Afterwards she is wasted supply until you can spare enough liquid mana to push her to Winged Maiden.)

In mid game you want to add/upgrade:

• 2-3 Troll Hurlers. (You do not need the final upgrade for quite a while; you will get an additional one for free.)
  
• 1+ Troll Chargers. (The final upgrade is comparably cheap but you don't need it yet)
  
• 1-2 Hunting Packs. (One is a guaranteed drop a second one is really useful)
  
• 1+ Winged Maidens (very expensive at this stage of the game).
  
• 3+ Fire Archers. (If you manage to get more than 3 Longbowmen you can skip upgrading some of your Slingers and save a lot of resources)
  
• 3 Thunderers. (Yes, the liquid mana is somewhat wasted if you sell them but you want 6+ anti-air units when you start the swamps; upgrade them in-mission against swamp dragons as needed).
  
• 1 Phoenix. (support for outrider detachments and main battle tank)
  
• 1+ Monster Hunter. (Anti-air for your main battle line, don't send it out to capture, use 1-supply units like Cleavers or Maidens and a Phoenix)
  
• Ditch your Cavalry when you reach the swamps. (Maybe keep one as a scout, in particular if the 0-supply recon loot drop did not happen yet)

In late game you want those numbers to go up to:

• 3-4 Siege Trolls in total
  
• 2-3 Monster Hunters in total
  
• 3-5 Armoured Trolls in total (EDIT: Winged Maidens are now viable too and can substitute 2 melee trolls)
  
• ALL the Fire Archers

This should leave you with some wiggle room to emphasize the units you feel comfortable with - in particular in late game.

To get a somewhat different perspective on army composition in a TL;DR style you can visit some tips on units by VladK02. They make some good points and have a (somewhat) different approach than the one this guide is based on so their valuation differs a bit as well. Imho my approach makes your army stronger and is less reliant on item drops (trading it for Fire Archer drops, which can be forced without cheating by killing off unwanted drops) but VladK02's army certainly is very strong and good enough to beat FG2 on Legend without major problems outside of the worst parts of the swamp.

If you want to play on legend you probably know what you are doing and you will want to adapt the army list to your taste. The following sections should give you enough info to do so without being frustrated about wasted resources later on.

Before we discuss unit types we neet to make sure that we are on the same page concerning game mechanics.

Free and accessible hexes in range of an enemy unit (preferable several of them) are opportunities to attack from. They can be considered a resource and I will call them open hexes.

Quite often the number of open hexes is very limited because at least initially your units are either slow or very slow. The average movement range of 3 hexes is low already but if there are forests, rivers or swamps (there always are) this can go down to 1 for many units. So, it is hard to get into (melee) range of an enemy (or just to go anywhere really). This severely limits the number of open hexes and it can be compounded by additional hindrances like mountains or ambusher. Open melee hexes without river/swamp debuffs are particularly precious because the AI uses acceptable positioning and makes you cross rivers/swamps. Sometimes open melee hexes without debuffs do not exist at all.

Once you switch from fighting battlegroups to fighting armies at the end of mid game there will be so many units around that the number of open hexes is even more of a bottleneck to overcome if you want to actuate your full damage potential.

Moving a unit and having it attack an enemy are two separate actions and should be treated as such. If you move up all units before the killing starts, you can:

• optimize XP distribution.
  
• move in all buffs and debuffs (banners, horns, ...).
  
• get a better visual idea on how to allocate your attacks and what sequence to use them in (the effect of your buffs will have is very hard to calculate precisely without trying).

Nothing stops you from moving a ranged unit into an open melee hex and to attack from there. This is a design mistake imho. The enemy should be able to retaliate if you stand next to them while you attack anything (unless your unit is a skirmisher). That is not the case though so there is no downside to using ranged units in melee hexes other than them being blocked for melee units. There are several upsides to filling the melee line with ranged units:

• you can kill or soften up enemies further back.
  
• you can kill stuff on the frontline and create a new and open melee hex.

The last point is more important than it seems. It increases the number of high-quality open hexes. That means, you do not want to move in your melee units until the last moment which makes them even weaker than they already are by being reliant on open melee hexes.

So why bring melee units at all you ask? Well, glad you asked! You should not. Melee units are a liability. I will go into detail on the exceptions in the sections about them.

In FG2 most units have a morale score that determines how easy it is to route them. A consequence/mechanic that is not immediately intuitive is that in FG2 a unit's resistance against magical damage is not fix because it takes a hit whenever a units morale is lowered. This means that by killing off individual units you weaken the rest of the army. If you combine this with mass-cursing it allows you to hit extremely hard with all units dealing magic damage (and one-shotting almost anything with Fire Archers).

The main source of morale damage on a unit is witnessing an attack dealing massive damage vs. an ally. Which is exactly what this army does. The secondary sources of morale damage are artefacts and spells. You should incorporate these whenever possible. Sometimes it is worth it to summon a bear purely to let it roar.

With this army (or any army really) you are trying to make sure that any enemy unit you encounter dies after two attacks from your troops. This is not possible immediately, of course, but you get there fast and should be able to reliably do so in (early) mid game. In late game you should be able to kill key enemy units (heroes in particular) in two attacks, lowering the morale of the army enough to start one-shotting weaker units, which allows you to kill stronger units in one attack and to rout all survivors left standing after you run out of attacks.

The main exception to this target sequence is the transmuter. When you encounter him you will probably be too weak to kill him effectively. This is true for quite a while actually. So you want to focus on slightly less high profile targets first to break his morale before taking him out. His death is still the single highest priority because of his Transmute Life spell that kills damaged stacks off.

To be able to 2-shot consistently you need to be able to allocate attacks to units that are susceptible to them (the game shows you the relevant parameters in the top left corner before your attack, which is quite handy) and/or to create such weaknesses. Your main debuffs are cursing and morale bombing. Your secondary options are harassing and transmuting armor. The first one is quite useful if done alongside a curse (or on units that cannot be cursed) and the second one is only needed/sensible in late game against the absolute hardest of tanky threats.

All of this means that open hexes are not created equal and that you need to be able choose which unit to put into which hex. This re-emphasizes the need to maximize your mobility once more.

Units carrying the keyword/trait "defensive fire" will preemptively attack/retaliate if an adjacent unit is attacked. I will call that overwatch (innovative I know). Overwatch is surprisingly powerful and surprisingly useless. The downsides are:

• You cannot position your Fire Archers and Slingers in such a way that they cover your front lines effectively. Your priority is to go in and do damage - you do not want to compromise that
  
• Slingers do very low damage if they are not adjacent to the enemy
  
• The AI is clever enough to draw overwatch with shielded unit and tanks

While overwatch is reasonably useful in (very) early game, it shines once you have enough Fire Archers (you never have enough Fire Archers) or just lots of magic Missile units in general. Enemy units that can handle magic damage are much less ubiquitous than shielded ones and after you went in and decimated the enemy battlegroup/army ("nonaginate" would be more appropriate...) its morale will have taken a massive hit, strengthening your overwatch significantly. In addition: while you cannot route certain unit types, those are mostly the same ones that are susceptible to magic damage from the get go and will go down to overwatch anyway.

The TL;DR gives you the army list and differentiates between the stages of the campaign. The sequence in which to upgrade or recruit your units depends on your item drops, which volunteers you can find and on the challenges the story and campaign throw your way. So, I will not go into details in this guide other than giving you a few pointers. Concerning resources:

• Gold is balanced perfectly to keep you progressing nicely.
  
• Weapons will be your bottleneck in early game and mid game. They become ubiquitous in late game.
  
• Armor is ubiquitous almost the whole time (because most units that need it are sub-par).
  
• Liquid mana will be extremely rare in early game (you can cheat and try to get a random drop from one burial site per map), common in mid game & ubiquitous in late game.
  
• Supply is what defines the strength of your army. The maximum you can have is 53. If you can choose between missions you should look for those that increase your supply.

You can upgrade your units within mission and you should do so. You should hold back on spending resources until you are able to train your units - and remember that new heroes bring new - and expensive - training options.

A game mechanic that deserves its own section is "Loot".

Loot drops seem to be predetermined in form of a chain, which means you get the same loot if you check one or several locations in one turn then reload and try the same again. Certain actions reset the loot chain though which allows you to manipulate the content of loot locations. To call them "chains" is not really accurate but quite intuitive for those of us without a background in math. (What I call loot chains are ordered graphs with edge choices that depend on the kind of loot locations you visit and where certain loot locations are clustered into equivalence classes). So here is what you want to know about loot locations:

• Loot locations with the same name are not differentiated in the loot chain (= they form an equivalence class).
  
• There are story related loot locations that are not marked as such. These do not change when you reset the loot chain.
  
• Camps are not treated equally. Some camps are volunteer-camps, some offer resources (weapon, armor and gold).
  
• You can only get one unit of volunteers per map - unless you lose a unit (I think) [Edit: as of 2021 this is not or no longer true in the Empire campaign so it might be wrong in this campaign as well]. The lost unit needs to be an actual unit that spawns mana and I did not check whether mercenaries count.
  
• Damaging an enemy unit resets the loot chain (a new graph is generated).
  
• Ending your turn resets the loot chain.
  
• Entering location type A changes the loot for all location types but does not reset the loot chain (=you are still on the some ordered graph, just one node deeper. I am not positive whether the branches are interconnected but think they are not).
  
• Raiding results are part of the loot chain.
  
• All raiding locations are treated the same by the loot chain (= they form an equivalence class).
  
• There is something weird going on with the raiding location when resetting the loot chain. I assume that the reset function has a bug and it somehow references the last graph that was built. This seems to be an issue relevant only for raiding, the other resets seem to be actual resets.

In other words: you can attack an enemy and try to loot a/several locations and get different stuff than you did before.

Obviously, I did save-scam quite a bit in the beginning because random loot frustrates me in a game but I stopped and would advise against starting to do so in the first place. It is not necessary (unless you don't find any Water Boots - you really need those in the swamp or you will be frustrated, EDIT: the movement in the swamps seems to be patched. I will not test that though, those missions are not really one of the games highlights - hopefully they are less painful now). Most artifacts are useful and the developers patched in some stuff that allows you to get rid of unwanted artefacts and that makes gold very useful later on.

That being said, if you do want to cheat I would advise setting up several loot locations to be raided in succession and then writing down the loot chains for different numbers of attack. Attack 0 enemies and check all locations, attack 1 enemy and check all locations.... This gives you a number of loot chains to choose from and if you are digging for a certain artefact it drastically increases the number of tries you have (depending on the number of locations you raid, of course). Purple artifacts don't seem to be part of the regular drop tables (the story will tell you when they are) This changed for the Empire campaign so maybe it was changed retroactively for the Barbarian campaign as well. Keep in mind that ending your turn also resets everything. If you don't find any loot chain you like, you can try again next turn.

If you do want to save scum, here is my take on what to prioritize (non-purple only, all the purple stuff is excellent).

God-Tier

• Magic Ring
  
• War Banner
  
• Water Boots
  
• Horse Token / Striding Boots

Excellent

• Cursed Amulet (less useful in late game)
  
• Death Mask
  
• Weighted Spears (can be useless in late game)

Good

• Horn of Courage
  
• Slash of Blackness
  
• Spirit Mask
  
• Helmet of Health
  
• Plague Doctor Mask
  
• Mana Elixir

Ok

• Spiked Bracers
  
• Chain of Armor
  
• Restoration Potion
  
• Belt of Bear's Strength
  
• Diary

Do take this list with a grain of salt though - artefacts depend on your army composition. Magic Rings and War Banners being the only exception. Two Magic Rings on a Fire Archer are spectacular and War Banners stack for each character that carries one - bringing your whole army to 100% magic resistance. You won't get attacked anyway but it is cool nevertheless (the increase in attack damage is not that relevant. It can be an advantage if it allows one your units to one-shot an enemy. Otherwise is it negligible because almost every enemy unit is dead after two hits anyway).

The game helps you by organizing its units into "types" (or classes or...). The way the game differentiates between different unit types is quite opaque though - not just if you are new to the game. So first let us clear up what the game is trying to tell us.

Take "Light Shock Infantry" (the basic male unit) and "Light Spear Infantry (the basic female unit). The important parts are "Shock" and "Spear". That is what I will call the type of unit we are talking about. Almost all prefixes like "Light", "Heavy", "Magic" and so forth only differentiate between different variants of a certain unit type like "Shock". The suffixes used by the game mostly describe the movement type of a unit, think "Infantry" or "Cavalry". For now, we ignore all of prefixes and suffixes and look most important bit: the unit types available.

Using the games logic, the types of units you can field are:

• Shock
  
• Axe
  
• Spear
  
• Missile
  
• Recon
  
• Scout
  
• Skirmish
  
• Artillery
  
• Support
  
• Leaders
  
• Beasts
  
• Animals

A somewhat long list but be can clean it up quite a bit.
Recon and Scout are the same type so we will ignore "Scout" (it being the Imperial "Recon"). "Beast" and "Animal" are a mis-named unit types (the mistake was introduced mostly with the Onslaught DLC). Wolves (Animals) should be called Support and the flyers should instead be called by their actual type and be given "monstrous" as a suffix (and "animal" needs to be a suffix to signal that they can be charmed). "Aerial" should be used as the unit type for flyers, not as a prefix (and I will just use "Flyers"). Skirmish cavalry works completely different from any other unit in the game so it is its own type. Leaders should be called support.

So the new list of unit types is:

• Shock
  
• Spear
  
• Axe
  
• Skirmish
  
• Skirmish Cavalry
  
• Recon
  
• Missile
  
• Artillery
  
• Flyers
  
• Support

For the discussion of which units to pick and when to transition into another army composition we need to create some clusters. Those are: melee (Shock, Spear, Axe, Skirmish, Recon), medium range (Missile, Support), long range (Artillery, Skirmish Cavalry) and Flyers. The reason we choose these clusters is pretty self-evident: in a perfect world hexes closest to the enemy should be filled with melee units then ranged units then artillery while flyers can be positioned anywhere. So units within one cluster compete for spots in your army (and flyers compete with almost everything else at once - even with their own unit type).

For detailed statistics on all barbarian units you can take a look at the overview FG2 Barbarian Units Review by Virgil-SKY.

Shock units get a second attack when they are on the offensive. Their attack is called a charge to differentiate them from a regular melee attack. Shock units have the highest damage output of any unit in the game - twice that of most other melee units. They have very good mobility in forests and several very useful offensive and defensive traits. All that makes them the best and only choice when recruiting melee units.

There is nothing special about the attack of Spear units. Their strength is that they break charges when being attacked. They are meant to counter Shock units but their own damage output is laughably low in comparison and the Shock unit can just attack someone else. Their damage output is lower than what a Shock unit can do without its second attack and they do not deal magic or siege damage. Their mobility is horrible compared to Shock units. They are completely useless. There is one exception: one spear unit (the Winged Maiden) is an undercover Shock unit.

There is nothing special about the attack of Axe units. They are given shields that make them resistant to missile attacks. They are meant to counter Missile units but their own damage output is laughably low in comparison and the Missile unit can just attack someone else. Their damage output is about the same compared to what a Shock unit can do without its second attack and they do not deal magic or siege damage. Their mobility is horrible compared to Shock units. They are completely useless.

Skirmish units can attack in melee without triggering a counterattack. This can be useful but it does not increase their damage potential which is - you guessed it - comparable to that of Spear and Axe units which puts it at half of what a Shock unit can do. They get shields and their mobility is as good as that of a Shock unit so they are only a bad unit choice and not a terrible one. There is no reason to ever get a skirmisher.

Recon units do triple damage when they attack from hiding. The problem is that they start out at half the damage potential of everyone else. This means that even if you can activate their gimmick they fall short off the damage of a Shock unit. They are supposed to be scouts and get better vision range & a skill that allows them to spot other Recon units in hiding (used instead of attacking). They do indeed have good mobility and they are the only ground unit that can climb mountains. Unfortunately for them the Witch-Hero carries a cheap spell with long range that can scout just as well while being able to summon scouts as well as combat units with better stats respectively that can cross mountains as well. You should not recruit any Recon unit but they are a fun addition to your army that gives you more options when planning capturing routes. You might get one for free from a loot drop that you will want to keep because it does not cost supply.

There is a melee support unit - the Thane. It is a trap though, a wolf mother is the much better choice for all intents and purposes. If you really want to get Thanes you should wait until you can train your units before upgrading them to become a Thane. Thanes count as heroes and cannot be trained. By the time you can train your units the Thane is even more useless though than earlier in your campaign.

There is only one choice when it comes to melee units: Shock units massively outperform the competition. The good news is that almost all Shock units are viable.

Berserkers and Cleavers
They do very good damage and their traits give them decent survivability. They can easily be brought to 100% magic resistance. They are good at:

• leading outrider detachments going for loot in early game and early mid game (until you can afford Winged Maidens).
  
• triggering ambushes in swamps - which is a much bigger problem than you probably anticipate.
  
• holding shrines in the swamps.

A good unit that is outperformed by the Winged Maiden in utility & by both the Maidens & the Troll in combat. Berserkers are very good in the early game because they do not cost liquid mana and are already offering many of the strengths of Cleavers.

Winged Maidens
They have good resistances and excellent movement range. The reason that they can be considered undercover Shock units is that they can jump-attack which counts as a charge attack (=double damage). Considering our goal to kill everything immediately this makes them a de facto ranged Shock unit. Their strengths are:

• Their jump attack has a very high range which opens up new hexes.
  
• Their mobility and durability make them the best choice to hold shrines
  
• Their mobility makes them the only unit able to make good use of plate mail (apart from a frenzied Falirson)

Their weaknesses are:

• Their jump is blocked by air units which is a pain because up to 25% of the enemy battlegroups and armies consist of flyers and your own flyers take their place when they kill them - blocking your maidens again.
  
• You cannot easily boost their damage output via artefacts because their jump attack does not formally count as a charge attack and because they do not do magic damage.

Toss-ups:

• They are too squishy to jump into the middle of the enemy army but they don't need to because they stay put after jumping if they don't kill their target. (EDIT: jump now fortifies)
  
• They deal normal damage while offering the best armor penetration in the game. Magic damage is still more desirable in most cases but your Missile Units, your Supports and most Heroes all deal magic damage so it offers your more flexibility if you do not bring too many Maidens.

The next patch is... EDIT: Fortify is now actually useful. You no longer have to stand still to toggle it. In addition it activates after winged leap. This helps the Winged Maidens massively in engagements and in the rare situation that you are falling back with your army.
All that being said: the buffs to fortify & jump made Winged Maidens the best 1-supply melee unit by an ever bigger margin. You want at least 1 that you send out to capture shrines that are hard to reach otherwise. Armoured Trolls are a lot more robust & do splash and siege damage - but 2 Winged Maidens attack twice.

Armoured Trolls
These get better the longer the game goes on. They start out very strong because of their regeneration ability and their very good resistances and health. On higher unit levels & later on in the campaign the regeneration becomes irrelevant but by then they have become the best unit in the game:

• They do siege damage which means that they are the only unit that can kill the strongest enemy ground units reliably.
  
• They do splash damage every few turns (2x their normal damage on the 3rd hex, while attacking two more enemies). The only other option for splash damage are the Air Elemental & Chain Lightning (both spells on the Witch hero) which both cost mana (the elemental, not its attack).
  
• With pockets, their damage can be increased while bringing them up to 80% physical and magical resistance.
  
• High health is amplified when leveling up.

This means they are an essential part of any late game army where their main downside - being 2 supply - is not as relevant. When open hexes are exceedingly rare, only Trolls and Maidens can get their melee damage in.

Werebears
While they are not nearly as bad as the non-Shock competition, they are a not a strong choice. They cost one supply compared to the 2-supply Armoured Trolls and have excellent survivability in drawn out engagements for their cost (Trolls still dominate, of course). Their downfall is the scarcity of open melee hexes, the lack of drawn out engagements and the high quality of the other choices among the Shock units.

First off: keep in mind that every ranged unit is automatically a skirmisher at the time this guide was created. In fact, they are skirmishers+ because they do not trigger overwatch. Both of that might (and should) get patched in the future.


Slingers, Wolf Killers & Thunderers
Their damage is bad but their mobility is good and they have overwatch. Their point-blank damage makes them viable in early game but is irrelevant later on (and there might be a bug, where point blank does not trigger against Skirmishers). Wolf Killers are quite expensive and stay at range two so you should only upgrade your Slingers in an emergency.

The biggest strength of Slingers is that they have no competition. They are the only Missile Unit available and you desperately need ranged units. If you can get Imperial volunteers early on you can skip Slingers altogether.

Longbowmen & Fire Archers
Any group of Imperial Volunteers can be turned into Bowmen so it does not matter which one spawns. (I got quite a few Peltasts, one group of Hunters and no Spearmen so the chances might not be evenly distributed.) You can skip Bowmen and go straight for Longbowmen once you have enough weapons (I would get Stag Lancers first). Decent damage, range three, good mobility and Ambush make them a very strong choice.

Fire Archers are the best 1-supply unit in the game (for the Invasion campaign!). If you give them Magic Rings, they get up to 272 damage late game (with offensive traits from training on top of it). Thunderers need a buff. I would try 200% point-blank damage or (better) morale damage.

Centaur Archers
The damage of Centaur Archers is pitiful so you cannot use them instead of Fire Archers. In combat they are worse than upgraded Slingers. Which means that they should not be considered Missile units but instead as Support units supplying a pathfinder aura. That means they compete with Hunting Packs for slots in your army. Their advantage over wolves is that they have a ranged attack with range 3. Centaurs are available in late mid game which means that the wolves' better mobility can be overcome via training and the wolves' strength against animals is no longer relevant. All in all, Centaurs are the superior choice for a Support unit that delivers a Pathfinder aura, an aura that is extremely useful (and cannot be recreated with an artifact afaik).

There is one problem though. You get the option to get Centaurs quite late in your campaign and if you get the option to hire them, you decided against acquiring 5 supply. FIVE SUPPLY. That translates into all kinds of massive disadvantages just so your wolves can have a ranged attack they will hardly ever use. One example would be two additional Winged Maidens, an additional Armoured Troll and an additional Fire Archer that are not currently pummeling the enemy. Those alone can take on a small battlegroup. You can safely discard anyone's opinion who advocates for Centaurs (unless you activate "scaling" which would, of course, defeat the whole purpose of acquiring supply and building up your army and has no place in a grand strategy game based on that premise exactly).

Hunting Packs
The packs' pathfinder auras are essential to keep your army moving at top speed. The upgrade to Hunting Pack does not cost weapons and Packs have decent damage (excellent damage against animals) which makes them viable in combat. In early game (when you are not strong enough yet to just plow through the map) on maps where you don't need to send an outrider detachment into some forest you can park your guaranteed drop of Wolves next to your Skirmish Cavalry.

You want a second group of wolves soonish. So, while you are digging for Imperial volunteers you don't need to kill off wolves if you happen to find them.

Thanes
Thanes are not ranged you say? Exactly. They should be (or better still they should get a third artefact slot). You do not want or need them in a melee hex so you don't want or need them at all. You want Wolf Mothers instead - even in open melee hexes. Thanes can carry an additional artifact and they can debuff enemies. Their poor damage output more than neutralizes the debuff though (which is gone after one turn anyway). They do not have magic damage or armor penetration. They are expensive. Their resistances are not that good for a tank and their mobility is horrible. Another nail in an already tightly sealed coffin is that they cannot be trained - which is a design decision so bad that it is a bug imho.

Wolf Mothers

• They can carry an additional artefact.
  
• Charm works on Pegasi and the AI does not de-prioritize charmed units.
  
• Bears can debuff morale for a huge group of enemies.
  
• They have a ranged attack and their range can be extended if you find the right artefact.
  
• They are one of the best tanks in early and mid game - in particular once you can equip them with a Plague Doctors Mask (health artifact).
  
• They can be trained (as opposed to the Thane).

Their attack is not particularly strong but it offers magic damage when that damage type is still rare. The attack being ranged it can easily deliver debuffs (if you have the right artefact) in particular if you put the Wolf Mother on a melee hex - which you want to do anyway because she is a decent tank. You can attack without entering rivers/swamp (as opposed to the Thane again). They are cheap, mobile and their utility is excellent. You want to get one with your first liquid mana and you want another one to cover the rest of the map. You can get the second one for free during your campaign so I would advise not to recruit a second one.

Stag Riders & Stag Lancers
Stag Riders are very cheap which means they offer the earliest/easiest source of magic damage. In addition, they have excellent mobility in open fields and can operate in most environments if you find the right items. They can attack air units and while they ignore zones of control, they do trigger ambushes. Their retreat mechanic is a matter of opinion. I dislike it because you lose a turn (or two) and the random nature of the direction they flee in can easily get the unit killed.

The attack mechanic of Skirmish Cavalry is quite counterintuitive. They ignore zones of control, are skirmishers and they move back for free after they attack. So, to have the right mental model you should consider them artillery pieces with solid shot (Troll Hurlers being the artillery pieces using grapeshot). One synergy that is not immediately obvious is that your wolves give your Skirmish Cavalry (your solid shot artillery) 2 hexes of additional range - which it can use to cross a river or forest or...

One additional strength of the attack mechanic is that you can (and will) use it to scout enemy positions. The major weaknesses of the attack mechanic are that you Cavalry can be "caught" by ambushers and that it triggers overwatch from units you have not been aware of before the attack. Secondary weaknesses are that the hex you are attacking from formally is not the one you are standing/starting on. Early on this is a disadvantage because your army is not yet overwhelming and consistently pushing so your buffs are not close enough to the enemy lines.

All in all you absolutely want to bring a couple of Stag Lancers until you hit the swamps. Then you want to ditch them all or keep one as a scout that has obscene movement range and can finish off stronger enemies. That one can be upgraded to a Wind Rider (the upgrade does not help them at scouting).

Troll Hurler & Siege Trolls
Hurlers demolish enemy units consisting of large numbers of low health troops and they attack at range 4 - at a time when most if not all of your ranged units attack at range 2. This gives you the typical strengths of artillery in games against AI. You can soften up enemy positions, you can attack accross mountains and rivers. You pretty much always find an open hex for a unit with range 4 which keeps them relevant all game (even if they have to move to attack). In addition, they have several strengths that you would not expect from an "artillery" unit:

• They have very high mobility.
  
• During early game and early mid-game your Hurlers rival your best tanks - the equally 2-supply-costing Troll Chargers - in tankiness.
  
• Until after the swamps you might not field more than 1 Troll Charger while you might field up to 4 Hurlers (including the one you get for free) - making them your primary (off-)tank.
  
• They can deliver debuffs.

The last point does not seem surprising at first but the high range and the option to equip an artifact effectively turn Hurlers into spellcaster. In fact, the best way to think about them is as spellcasters that need to channel before they can dish out their full damage. (I suspect that the unit was indeed a spellcaster in an earlier build and the wording was changed from "channeling" to "heavy weapon" to make it easier to understand/use). The goal of our army is to kill every enemy unit in 2 hits and some in 1 hit. The Hurler delivers on both fronts. It can take out quite a few enemy units in one hit (again: at a time when no other unit in your army can do so) and if it is equipped with a cursed amulet it can soften up most enemy unit far enough for them to be killed with the next attack. This also means that the main weakness of your Hurlers (the need to stand still to deal full damage) is a lot less relevant than it seems.

You do not need the upgrade to Siege Troll for quite a while. In fact - you do not need to do so at all until liquid mana becomes ubiquitous - instead you can give them an additional artefact slot if you find good items to buff/debuff with.

Imperial Artillery
There is a random drop that gives you access to one piece of Imperial artillery. It is not worth it to spawn it unless your army is at max supply and you can go over that. But even then - your supply will go up further and you will want to discard the unit again.

The number of flyers you field is a a personal choice. Everything between 2 to 7 of seems reasonable and them being 2 supply each means that a huge part of your army is purely a personal choice. As it should be for a strategy game.

Most flyers cost too much supply for what they can do. The only flyers that are not out-competed by another unit (or several) are the Monster Hunter and the Phoenix. Those two share a few similarities so we can discuss their usage in one go:

• They are both melee and super-melee. They attack adjacent Flyers (which can retaliate) but can only attack ground units on the same hex (dive attack). Which makes them horrible against ambushers.
  
• They both move into the hex of an enemy Flyer that they have defeated. That can be a problem because it blocks Winged Maidens and some other attacks/spells you will want to use.
  
• They cannot ambush.
  
• They do not get buffed by a pathfinder aura.
  
• They can stop enemy air units from killing off weakened units in your army.
  
• They cannot move over an enemy unit and attack later (at least I did not find out how - CTRL does not work). This seems to be a bug/oversight and it means that you have a hard time positioning them optimally before the slaughter starts. This reduces the number of open hexes massively if you want to split up movement and attacks - which is acceptable if you use them mainly as anti-air. [Edit: Ha! Someone in the forum wrote that you can use "move" - normally bound to "m" to move without attacking automatically. It sure took me a while to learn that...].

Both viable flyers focus on anti-air (the Phoenix less so than the Monster Hunter) which means that there is such a thing as fielding "too many" flyers. Both Monster Hunters and Phoenixes are essential to shield your army against enemy flyers and both excel as anti-air on the offensive as well. Once there is no more enemy "air" to fight they get harder to use effectively (considering their 2-supply cost).

Monster Hunters
Monster Hunters are the best anti-air units in the game and enemy air units are a massive mid and late game threat (the only actual threat in the whole game are certain mid game flyers). The damage ouput of Monster Hunters is not quite high enough for a 2-supply unit but their mobility, their ability to intercept enemy flyers and their ability to take out the most dangerous threats make them worth it. Notable points:

• Their net sounds useful but you will only use it in one or two swamp missions if at all. There is a summon for entangling units (which you don't need as well) and to use the turn of a 2-supply unit to disable one enemy is a waste in late game. It only slows you down.
  
• One major strength of theirs is that they do NOT deal magical damage. Almost every thing else does, so you want flexibility. Winged Maidens deal physical damage as well but they cannot attack air units and are a lot less durable.
  
• They can carry 2-3 artefacts and can be positioned in the middle of your army (while still being able to attack an enemy flyer) which makes them a very useful in late game if they carry buffs.

The swamps are the only missions that are actually dangerous and they can be a lot easier if you bring Monster Hunters (Phoenixes are useful as well) So if at all possible you want 2 or even 3 Monster Hunters to fight in the swamps. In hindsight I should have ditched 2 of my Skirmish Cavalry immediately to get my first Monster Hunter and maybe ditch a Hurler as well (I got the free one when I was at 3 already) to get second Monster Hunter. Hurlers are quite useful all game long but the Monster Hunters take the edge of the hardest parts of the game.

Firebird
Phoenixes (I will not call them "Firebirds") are the best main battle tank in late game (because the AI has poor target priority).

You want 1 Phoenix asap to be able to use Cleanse (a cheap long range spell that removes all buffs and debuffs - you need it mainly against harpies and against petrify and blessings from certain enemy units) and to use it as your main battle tank within you outrider detachment(s) that go capturing or for secondary objectives.

A weakness that is not immediately obvious is that a Phoenix is immune to psychological effects. So it cannot be buffed by war banners - which is irrelevant in an outrider detachment but a massive drawback when it is with your main army. This gives you an additional reason to overextend with your Phoenixes (one or two artifacts to buff their resistances and it/they should survive one turn in the middle of an enemy battlegroup or a smaller army). If a Phoenix' level is high enough to allow it to survive without artifacts you give it a mask to reduce damage and morale - the last one being massively useful in late game

I would recommend a Phoenix as your first flyer and 2 or 3 Monster Hunters afterwards.

The most important summons are:

• Ancestors. They are reasonably cheap, can cross mountains and buff each other which makes them the best choice early on when mana is very limited and your army has not yet grown (and you might not have access to Air Elementals yet).
  
• Air Elementals. They have a magic-based area-of-effect spell/attack that the enemy cannot retaliate against, a haste spell, great mobility and good health. Both of those spells are free. The Air Elemental is ridiculously overpowered and needs to be changed. (the developers should limit it to 2-at-a-time or add a 1 mana cost to their spells or make them one-off or...).
  
• Bears. They can lower morale and hold a position for quite a while. Eagle Bears hit hard in addition. The morale debuff is their raison d'être though.
  
• Spitting spiders. In some fights against swamp dragons you might want to disable a threat that you cannot kill fast enough. I would (and did) get an Air Elemental instead but that is probably the wrong call.
  
• Bats. In theory you need some flying 1-mana summons to scout with but I just used the spell from the Witch Hero, checked and reloaded. If you don't want to do that (it is cheating after all) you want a couple of those from your Wolf Mothers. EDIT: Something I missed is that bats are very useful as tanks. They go down relatively fast but that makes them BETTER at tanking (given their low cost). The reason is - again - that the AI chooses its targets very poorly. The AI will try so hard to kill bats (hurt ones in particular) that they will put some of their strongest units (flyers in particular) in harms way AND waste their attack instead of finishing off a more important unit of yours. A bat can often tank three (or even more) attacks before going down (it can be buffed by horns) which makes it massively overpowered for one mana. Scouting and attacking archers who have spent their defensive fire are both nice-to-have in comparison - and those alone almost make up for a cost of one mana. That's what you get for cheating.... you miss one of the best defences against flyers.

The other summons are not worth it. Most are appropriately priced for what they do but Bears, Air Elementals, Bats and Cheating cover all bases.

At some point you will get an artifact that gives the trait "strong" to all units summoned by the caster carrying the artefact. Once you have it, you will be pumping Air Elementals each turn with the Witch hero.

Using mercenaries brings dishonor on you and your cow. You are spending gold that you could be using to upgrade your troops. Mercenaries are unnecessary and buying them weakens your army. That being said: they are not all that expensive and you get 3 mana once they die. Get them, if you enjoy fielding them - in particular for the three harder mission (I am not sure whether you can buy them in the swamps...).

Max level is 10 so you have 10 skill points to spend.

Each hero gives you different options to train your troops. Apart from the two mandatory heroes the hero that buffs gives you the most import training options by far. Wanderlust and Magic Armor are essential.

You can find the detailed stats in FG2 Hero Units Review by Virgil-SKY. This is about builds instead and the names are de-spoilered.

Mandatory skills (6 skill points)

• Quartermaster und Master Provisioner are the second-best skills in the game after Transmute Life.
  
• Bigger Pockets and Even Bigger Pockets are needed to up his resistances and/or to carry buffs.

Recommended (4 skill points)

• Drill II gives units you hire on the campaign map (=your flyers) an XP boost. Strong but not all that powerful because "Volunteers" (spawned by Camps, some can be upgraded to Fire Archers) do scale with the average level of your units (my last 4 volunteers were all level 10 immediately) and once you are level 10 (to take full advantage of "half the level") your army is pretty big already - apart from archers, flyers and maybe a couple more trolls (that you can and will get from camps as well while fishing for Fire Archers if you leave two supply unused).
  
• Call Champion does not cost mana and it allows you to overextend on purpose. If the bait does not get killed it can retaliate with heavy damage. The auras needed to get to Call Champion are decent but only really useful in early game. You will not take damage later on anyway.

You absolutely can take the hammer upgrades instead. They keep Falirson useful in late game so they are probably the better option tbh. Call Champion is just a bit more interesting...
Famous and More Health are a joke in comparison.

Falirson is by far the best candidate to put frenzy on (there is an option in a mission). He also needs his mount. So, you should free it or help him (loot location in "Thieves in the night").

Unfortunately, VladK02 found a build that is clearly the best choice. I dislike it because I really wanted the XP-aura and the mana boost trait. In reality this hero needs to do two things though: spam strong Air Elementals und Chain Lightning II. So instead of taking that sweet early game boost and/or helping your whole army level quicker you need to take:

• Chain Lightning II.
  
• Raging Storm.
  
• Bigger Pockets and Even Bigger Pockets.

You use the pockets to amp magic damage and give her a mana extractor. I would take Summon Mist on my way to Chain Lightning II but only because you do not get access to it any other way. You will be summoning and blitzing when you have mana.

Mandatory skills

• Transmute Life.
  
• Bigger Pockets and Even Bigger Pockets increase their range and/or allow them to carry buffs.
  
• Shackles of Pain. You can cast this on enemy units. I was not aware of this until I read it somewhere. So not only does this make a unit invulnerable for three turns, it lets you utilize overwatch.
  
• Cleanse. Very useful - details in the section about the Phoenix.

If you want to cheat you can do so by taking Mirror Image while carrying mana potions (I assume this will be patched when the Empire campaign gets released). If you don't want to cheat I would advise against Mirror Image. Random positions are not acceptable, every hex counts.
Resurrect is nonsense because the unit loses XP.

This hero is an essential support for your army, being your mana generator. Do NOT let them leave. You need 2 liquid mana the first time their presence is in jeopardy and 800 gold (or 6 liquid mana if you are crazy) the second time. After that it is handy to have another 2 liquid mana in reserve for an optional bonus. So always keep two liquid mana around or look up when exactly you will need it. If you can't pay them, force them to stay. The resulting debuffs are almost irrelevant (for min-maxing purposes you can straight up safe the 800 gold and take the debuffs, but hey! They need that gold for their yacht! Maybe they leave you later if you do, but I don't think so.

Mandatory skills

• Bigger Pockets and Even Bigger Pockets increase their tankiness and allows them to get close and doom an army.
  
• Attuned II.
  
• Heroes Song.
  
• Doom.

They are a very straight forward hero carrying every relevant support spell there is. Transmute Armor is the only one I did not see an artifact for but that does not matter because you would put it on this hero anyway to go in a debuff/buff. Their ability to curse in retaliation is quite strong early on. Once mana no longer is an issue (=the transmuter arrives) you will be mass-cursing all armies and most battlegroups anyway.

Mandatory skills (6 skill points)

• Quartermaster und Master Provisioner are the second-best skills in the game after Transmute Life.
  
• Bigger Pockets and Even Bigger Pockets are needed for them to carry buffs.
  
• Army Stance March.

Army Stance March changes the dynamic of the game completely and lets your already highly mobile army travel maps without a single turn interrupting the slaughter. The debuffs are irrelevant because you annihilate the enemy in one turn and retreating actually gets good late game because your wolves push stragglers anyway and you cover so much ground that your retreating units will almost never go somewhere nasty. It does not matter what you take for the rest of their skill points. Their damage is almost irrelevant so even though you don't need them I would recommend the other two stances. If you have an emergency or made a planning mistake those stances can save you. Don't cast them when March is fresh though! It would be a shame to waste 50 gold for finishing the level a bit earlier.

The other heroes will probably leave you in mid-game but they are as straight forward to build as the hero that buffs. Some can stay if you make corresponding decisions but that is spoiler territory.

Some words on the three missions that are not quite trivial, even if you bring a strong army and know what you are doing.

That-god-awful-swamp-mission
(pretty sure it is called "Shrouded Coast" but it might be "Glowood")

You know, the one with 12 to 15 (if you are unlucky and the patrol gets activated alongside the battlegroup) unpleasant swamp dragons attacking a third of your army all at once. This can be a brick wall and could force you to reduce the difficulty (no shame in that!). The army composition we are going for in this guide with its focus on ranged units brings the best anti-air you can possibly have at this point but still: this one is HARD.

The strategy for the map depends heavily on where the AI spawns its massive group of dragons and on their initial movement. It consistently spawned them in the middle for me (I tried more than once...) but I would not rely on it.

You want to join your western battlegroup and the one in the middle ASAP. You need to keep to the edge of the map or you aggro the dragons. The battlegroup in the east can try to fight for a bit but I did move most of it west as well immediately (I left the stronger melee and a very small anti-air detachment to fight the non-dragon lizard army over there. Then you hold against the huge group of swamp dragons but baiting them to attack melee units you can pull back or summons.

Things I did not do that might help:

• You just might be able to aggro only a part of the dragons (if they fly off into a "good" direction on their first turn).
  
• It gets quite a bit easier if you already have Monster Hunters.
  
• You can think about summoning spiders instead of air elementals to web dragons (they are not "large") and to tank.

Thieves at night
Imho this is the second hardest mission in the game. Focusing an mobility allows you to beat it without mercenaries though (those are uncouth - they cost gold! Boo!). You want to pull everything back into the middle while grabbing loot, to hold out there (loosing temps is fine) and break towards the north east, circling the mountains to avoid the battlegroup to the south/south east.

It is imperative to kill as many groups of enemies as possible before they merge in the middle. The north east needs to be taken out if you want to break into that direction. (You can choose another direction but the forest and mountain ridge in the north east give you an advantage).

Here is a discussion about the mission, containing lots of exaggerations and lots of insults over those exaggerations. They still make some good points about the mission.

There and back again
Probably objectively the hardest mission in the game and at first sight not a good fit for this army (it being about being on the offence). If you know the map though this army composition is still by far the best option and will carve through the Imperials ridiculously fast. You want to drink 2 to 4 mana potions (pumping strong air elementals and normal bears), grab the shrines and the dragon, hold the riverbank (to break charges and to debuff the enemy standing in the water) with summoned bears and annihilate most of the lizards first with almost everything you have.

The riverbank is not the best place to fight the Imperials - there is a mountain ridge right beside the dragons lair which is perfect. That is not an option unfortunately because you lose control over the battlefield if you engage there. You cannot hold the two shrines and the lizards can consolidate their armies.

So about those stone skin shrines and the speed shrine (one stoneskin shrine was a regeneration shrine in the past or is one on other difficulty levels) as well as the dragon's lair:

• You do not necessarily need the shrines yourself but you don't want the enemy to grab them (the speed shrine in particular).
  
• The speed shrine (just east of your keep but across the river on an "island") can be held by an isolated Falirson equipped with enough purples.
  
• The southern shrine (almost at the edge of the map; south of the speed shrine) can be capped and held by a winged maiden supported by an eagle (preferably a phoenix) and the dragon. You need to run through spider-territory without getting webbed, so maybe bring another unit to bait the webs.
  
• The shrine in the north east (north east and comparably close to your keep) will be held by you anyway - this is broadly where you fight the lizard armies.
  
• The dragon lair can be found at the river bed to the south of the speed shrine.

There are lots of discussion about this mission in the forums but those are mostly weird. Probably not really on legend difficulty. The mission is not really hard, you just need to know the map in advance or you will suffer heavy losses.


This discussion is really helpful to choose between missions: The Mission Choice Spoiler Thread by Mhorhe. Not all choices and results are in there but it seems mostly correct and is low on spoilers.