Race / Classes
Start: Elf (Fire 1) - Priest
End: Mage 9 - Priest 5 - Inquisitor 1

Optional: Oracle 1 or 3

I choose Priest as a starter class instead of Mage because a) it gets us to Priest 2 faster and b) I find the starting equipment + stats better defensively. Confuse is a gamechanger, so you want that ASAP. The damage absorption of the starting armor is also quite nice (especially for early game). You might find a new armor quickly, but I've had runs where I didn't find anything until Day 2-3 so keep that in mind.

Early Game

• Magic Missile (Evocation 2)
  
• Fire Breath (Evocation 2 - Fire 1)
  
• Confuse (Enchantment 2 - Holy 1)
  
• Incineration (Transmutation 4 - Fire 1)

Mid Game

• Smite (Evocation 6 - Holy 1)
  
• Water Dance (Transmutation 2 - Water 1)
  
• Mage Armor (Conjuration 4 - Air 1)
  
• Fireball (Evocation 6 - Fire 2)

Late / End Game

• Magma Missile (Evocation 8 - Fire 2 - Earth 1)
  
• Gaseous Form (Transmutation 6 - Air 1 - Water 1)
  
• Mind of Steel (Enchantment 8 - Earth 1)
  
• Teleport (Mage 7)

Spell Hit bonuses: > 20 (over 22 if you can manage)
Defense (all): > 25 (over 30 is ideal)
HP: > 200 (over 250 if you can manage)
Resistances: > 20 (over 25 if you can manage)

Main goal for endgame is to a) make sure we don't miss and b) make sure we don't get hit (or worse - stunned). Physical resistance can be hard to come by if you don't find decent equipment.

The stats in this game can be very confusing for newcomers and even veterans alike. Since there are so many to choose from it can be hard to know which to prioritize and which to ignore. In general it is good to level offensive stats to a point where you can hit enemies consistently and take them out in a few hits and defensive stats to a point where you can stand in the middle of 3 enemies for a turn or 2 and survive. Ideally you can clear an entire Day without ever having low health (e.g. being below ~half hp with no hearts to pick up) except in extenuating circumstances.

Offensive
In general if exp costs are equal Fire Affinity > Magic > Evocation > Intelligence for this build. Fire Affinity and Magic both increase hit chance and damage of fire spells, whereas Evocation only improves hit chance and Intelligence only improves damage for spells. As Magic is typically cheaper than affinity (and affects ALL spells, not just Fire ones) it is generally the #1 priority. In terms of bonuses, here is what 1 point of each will give you:

Fire Affinity: +1 hit, +2-3 damage
Magic: +0.5 hit / damage
Intelligence: +1 damage
Evocation / Enchantment: +1 hit

Levels of Evocation will be more vital in late / end game when things start being much harder to hit. Levels in Enchantment are also useful for increasing the chance to hit for Confuse in late game. You shouldn't need any other offensive stats (e.g. specific weapons or Close / Ranged Combat).

Defensive
In general Dodge > Dex > Con / Resistance. Dodge gives a flat +1 Defense whereas Dex gives +0.5 Defense per point modified by body armor weight (+0.375 in light armor). Shield, Armor, and Strength should be leveled to the minimum needed to wear any equipment you find.

Stats should be leveled such that a) you are able to take a few hits if you get Fury'd or Mesmerized and b) they aren't extremely cheap compared to your next offensive stat ranks. If your next rank in Magic is 1000 and 10x that of any of your defensive stats and enemies are giving you 50-100 exp per kill you should strongly consider leveling your defensive stats a bit first.

Defense in and of itself is probably the most powerful stat in the game as it is what every damaging ability will target and will determine whether or not enemies can even hit you (e.g. like fighting late game bats with ranged attacks). If enemies can't hit you, getting hit by CC won't leave you at low hp or dead. Constitution and Resistance should be kept about even in costs so you can avoid those types of situations altogether.

In general, aside from getting Rebound Class Levels are not all that vital (although they do provide nice bonuses). Priest 2 is great early for the utility of an essentially free Holy affinity, and Mage levels are also useful in that regard, but in general stats > class levels. I typically get Intelligence up to 7-8 before starting to pick up class levels after that.

There are a few optional choices for class ranks depending on what equipment you find. Inquisitor 3 can be useful if you have found a lot of +Holy, and Oracle 1 or 3 can be nice for the regeneration + defensive bonuses they give if you have already met the stat requirements.

I use light armor throughout as heavy armor drastically reduces the amount of Defense you gain from Dexterity and Water Dance. Water Dance works better with every type of light equipment - that means weapons and armor but also shields. This makes it difficult to tell what equipment is better just by looking at it. Going unarmed vs using a staff was a +2 Defense difference, so I wouldn't even recommend using staves if you only have a buckler. Make sure to equip things to test whether or not they're better. If you are extremely unlucky, depending on your Dexterity it could even be that it is better to go without body armor. For my Pit Lord Perfect run I actually did this to great effect - in end game you could get upwards of +3-5 Defense just by removing it.

I use shields instead of books as the increased defense from a shield far outweighs that of the additional affinity from books. A single Fire affinity was giving me +1 hit and +2-3 damage on Fire spells which about evens out if you can find a good shield with Int on it. I'd much rather have +8 (or greater) Defense with a good shield over +2 Fire any day. For the rest of my equipment I prioritized stuff that boosted def / dex / int / con wherever I could. Also important to note - don't forget your ranged slot!

In terms of level choices, I tend to prefer Armor rack > Altars > Relics, and the rest I try to ignore. Ancient armor racks are great (unless you have amazing gear) as they will give you 4 pieces of equipment. This generally seems to provide helmets / belts / gloves / body armor, so if you're lacking any of those check there first. Second priority is to try and fill out your elemental affinities to +1 (ignore Death / Holy). Relics seem to provide necks and rings, so look for those if your affinities are all +1 and there is no Fire altar.

Books are worthless so we can easily skip those. Merchant seems to just give potions so are generally best avoided. I have absolutely no idea what the "benedictions" level does. I didn't gain any stats, exp, or affinities, so it pretty much just seemed like an empty level. The beast is generally a high risk pain in the butt for a small amount of exp (I got 360 xp for a young hydra on Day 3 which took forever to kill due to its regeneration), so it's best to avoid them if possible.

In general, the best strategy is to focus on fighting enemies 1 at a time, but a lot of times you will get thrown into a level surrounded by 3-4 or more and have to scramble. Confuse helps you lock down 1-2 enemies so you can take out a third, but since it only lasts ~3-4 turns more than that will be extremely difficult to keep up with the energy costs needed to do any damage. Mesmerize (Priest 4) can be very helpful in that regard as it will keep enemies in one place for much longer (~10 turns).

Early / Mid game
Magic Missile will be all you need for damage, however it cannot target enemies behind other enemies so in mid / late game you will want abilities that can hit your target (e.g. summoners) when you are surrounded. Smite and Incineration both can target any enemy in range so those will be very useful. Once you get Incineration you should generally use that over Magic Missile when in range as the damage ignores armor, so even though Magic Missile has higher tooltip damage Incineration will often still do more damage. Golems are especially vulnerable to Incineration as they have high Armor in general. Also note that it targets physical defense instead of spell so enemies that are hard to hit with Magic Missile may be much easier targets with Incineration.

Once you have Magma Missile and Rebound you should have little need of much else. If you can't get these before Day 5 you should make them your top priority. Magma Missile does ~50% more damage than Incinerate / Magic Missile, plus applies a Burn debuff which does a ton of damage. Tack on Rebound and you'll plow through enemies fast. The only times you'll really want to use Incineration is if you're having trouble hitting enemies (e.g. Giant Bats, Spirit Naga) or if you're having to Mesmerize enemies a lot.

Late / End Game
You'll want to make sure your abilities rarely miss. If you are missing a lot this could mean your +hit is too low or you're targeting the wrong defense. If leveled adequately, Magma Missile should really only have trouble hitting Bats and Gorgons.

While Line of Sight can be annoying at times it's worth pointing out that enemies also are affected by it so it can be useful to use that to your advantage. A well positioned melee enemy can stop pesky ranged enemies from hitting you while opening up opportunities for Fire Breath to do a bunch of damage. This is especially useful before you have Rebound.

Once you have Rebound, take advantage of the fact that it can bounce to enemies you can't see. It will only bounce if you hit the first target, so try and target weaker enemies first to maximize it's effectiveness. With Rebound, summoner type enemies go from being mildly annoying to an absolute joke.

Throughout the game you should abuse the fact that enemies often mindlessly follow you everywhere (e.g. around corners, into narrow passageways) which makes it easy to get them to clump up in order to Fire Breath / Rebound them down safely. Since most ranged attacks can't be fired through enemies the ranged enemies will often spend more time trying to get a clear shot which should give you time to get a few good AoEs in.

Bats
Bats suck. Bats suck a lot. They are generally a pain in the ass both because they tend to have high defenses (especially late game) and because they can cast Fury. Late game bats can be impossible to hit with Magic Missile (which makes no sense!), but thankfully they are always extremely susceptible to Confuse and should be easier to hit with Incineration.

Gorgons / Nagas
Gorgons can put you in a bad spot if you haven't found much gear in your playthrough and catch a bad Mesmerize. It is generally a good idea to make sure they are a priority target for Confuse / Mesmerize so you don't even have to worry about it. Late game Gorgons (Spirit Naga) are hard to hit with Magma Missile but Incineration works quite nicely.

Skeletons
Early game skeletons are no real threat, but late game skeletons (Obsidian) have a lot of HP and can do large chunks of damage with ease. Since undead can't be Confused or Mesmerized It is generally a good idea CC other enemies and take the skeletons out quickly before they get to you.

Vampires
Late game Vampires can cast Drain Life (Necromancer 3) which generally does quite a bit of damage. If you're not careful you could very quickly go from half HP to dead in a very short amount of time. Given that they are undead and cannot be afflicted with Confusion it is generally a good idea to find a spot to fight them where you won't be taking on multiple enemies at once.

The first thing you should do is spend your free affinity point (assuming you went Elf) for a level in Fire and get Evocation 2 ASAP for Magic Missile + Fire Breath. These will serve as your damage for most of the early / mid game. If you're surrounded by multiple enemies try and back around a corner so one enemy will pop out and you can use Fire Breath (which will often hit enemies around the corner).

Next, get Priest 2 for the free Holy affinity so you can get Confuse. As most enemies have low / non-existent Mental Resistance, Confuse lets you wreak havoc on most enemies without getting hit. Undead are immune to Confuse so Smite will come in handy in mid / late game.

For equipment, the main goal in early game is just to try and fill in as many slots as you can. If you can find a decent buckler and Leather / Studded Leather pick it up even if you haven't put stats into it yet.

By the end of Day 2 I usually have the following stats:
Classes: Mage 0 - Priest 2
Offensive: Magic 7 - Intelligence 3 - Evocation 4
Defensive: Dodge 5 - Dexterity 2 - Constitution 2 - Resistance 4

For the most part you should be able to breeze through mid game with just Magic Missile and Confuse. If you're having trouble with survival put more points into Dodge or try to get Water Dance and some light armor. I dumped points into Intelligence and picked up Mage 3 for the free affinity point (Fire 2). Priorities here are to fill out any empty equipment slots and hopefully get another

By the end of Day 4 I usually have the following stats:
Classes: Mage 3 - Priest 2
Offensive: Magic 8 - Intelligence 8 - Evocation 6
Defensive: Dodge 6 - Dexterity 3 - Constitution 2 - Resistance 4

Late game priorities are to get Magma Missile, Mage 8 for Rebound, and Inquisitor 1 for Fire Mark. Spend the extra affinity point on Fire 2 or Earth 1 if you don't have them yet. If you're missing any equipment or have mostly greens hit an armor rack location if there is one. I ended up getting Inquisitor 3 but the first rank is all you actually need.

By the end of Day 6 I usually have the following stats:
Classes: Mage 8 - Priest 5 - Inquisitor 3
Offensive: Magic 10 - Intelligence 10 - Evocation 9
Defensive: Dodge 7 - Dexterity 6 - Constitution 6 - Resistance 7

In the final level I bought an affinity and picked up Mage 9 for another one to round out my elementals (so I have 1 of each). I got Enchantment 8 and Transmutation 6 for Mind of Steel and Gaseous Form to be immune to pretty much every status effect, then put points into offensive stats since I was starting to hit less often (stupid Giant Bats). When you see a door to open (should be on floor 3 or 4) that is where the cultists are. There are actually 2 doors, so you should open the first as there is sometimes an enemy spawned in the hallway to the 2nd.

A key thing to point out is that this hallway is an amazing chokepoint for killing enemies in, so you should try and stay in it as much as possible. One of the cultists has an ability to teleport you randomly, which they will likely cast in the first turn or two, and could put you in the room with the children. If that happens you'll likely have to fight from inside there for a bit. If you can, stand in the doorway of the prison so the kids don't get out and Mesmerize the summoner cultist (the one in robes that doesn't look like a buff dude). You should be able to stand there and Mesmerize enemies on your diagonal so you can Fire Breath enemies in front of you to AoE them down.

If you're not sure how to summon the Pit Lord you need to kill the Princess (and possibly the children).

Depending on which achievement you're going for you'll want to make sure to pay attention to the Princess + kids as they can be killed by a rogue AoE (the enemies themselves seem to ignore them). You will likely get teleported a couple times in the fight, but you should have Teleport (Mage 7) which will help you readjust. As long as you take your time and are careful with this fight you should be able to get both achievements without any issues. Congrats!