Core Skill: Thorn Garden. Whenever you cast an arcane or nature spell, summon 2 fae thorns (nature + arcane) near the target.

General Strategy: Kill enemies, draw enemy fire, and block enemy movement using Fae Thorns spawned principally from casting Poison Sting and Magic Missile.

Build Strengths: Melee enemies and partially-open levels with small arenas where enemies can be surrounded by thorns.

Build Weaknesses: Early physical+poison immune enemies (ghosts). Levels with many chasms and few walls or floor tiles, where there's few spaces for thorns. Late game Arcane immune/resistant enemies. A small number of other enemies.

Poison Sting (1 SP): Does physical damage, applies poison, and spawns thorns.

Magic Missile (1 SP): Does arcane damage and spawns thorns.

Wolf (1 SP): Spawns a wolf and thorns. Useful for clearing Realm 2 (surprisingly difficult with only Poison Sting and Magic Missile), as a meat shield, and as a secondary source of damage.

Thorn Garden (5 SP): Spawns 2 fae thorns whenever the player casts an arcane or nature spell. Delay either Poison Sting or Magic Missile so you can take this at the end of Realm 2.

Shielded Minions (4 SP): Arcane minions start with +3 SH. Other minions start with +1 SH. Massively increases the survivability of thorns, which can now tank 3 hits before enemies can even start to damage their actual HP.

Arcane Combustion (4 SP): When a unit (including your own minions) dies to arcane damage, explode in a 12 arcane damage 3x3 which destroys walls. Useful for clearing out large numbers of chaff enemies like ghosts and imps. Early on, the help is especially appreciated against ghosts, which are immune to the physical and poison damage dealt by thorns and can therefore consume a lot of turns and spell charges if you have to pick them off one by one using Magic Missile. Also useful for opening up maps to quickly reach and destroy monster gates or line up large Cantrip Cascade blasts.

Note that you can and will get caught in Combustion explosions. It sounds scary but in practice the amount of damage you take in this way is manageable. Just be cognizant that if you kill an adjacent enemy using Magic Missile that you'll take a blast to the face.

Venom Spit (4 SP): Nature units get a 6 range 4 poison damage attack which poisons for 10 turns and has a cooldown of 4 turns. Your thorns have a ranged attack now (wolves too)!

Poison Sting - Acidity upgrade (2 SP): Removes Poison resistance, helping Thorns and Wolves damage Poison immune enemies (including monster gates!) using Venom Spit. Note that poison immunity is fairly common.

Nature Lord (7 SP): Nature spells and skills get +3 charges, +2 duration, +7 minion damage, and +10 minion health. This is a massive buff to your thorns. Note that the +7 minion damage applies to Venom Spit as well, but it does not apply to Poison Sting.

These spells and skills are the core of the build. By the time you're done, your thorns will have buffed health, damage, shields, and duration, along with both melee and ranged attacks. You'll be able to break levels open using Arcane Combustion and take down gates using Poison Sting (with Acidity) and thorns dealing both melee and ranged damage.

Void Spikes (7 SP): Anytime you or one of your arcane or undead minions takes damage from an enemy, deal 5 arcane damage to that enemy. This powerful retaliation attack covers multiple weaknesses in the core build. Physical+Poison immune enemies (ghosts) will get hurt when attacking your thorns. (I don't think anything is immune to physical, poison, and arcane.) And enemies with ranged attacks will take damage even if they stay out of range of you and your thorns. In particular, Aelfs with chain lightning will be killed - without Void Spikes, chain lightning has the capacity to damage an unlimited number of thorns (and you) repeatedly.

Cracklevoid (6 SP): Whenever an enemy takes arcane damage, deal that much lightning damage to 2 random enemies in a 6 tile burst. This tripling of damage synergizes with Magic Missile, Arcane Combustion, and Void Spikes. The effect is so great that it's common for Cracklevoid to take over as the #1 source of damage for the build.

Void Lord (7 SP): Arcane spells and skills get +2 charges, +8 damage, and +2 range. Big damage improvement to Void Spikes (tripled by Cracklevoid!) and Arcane Combustion. A nice overall upgrade for Magic Missile. And +2 charges for Mystic Vision and especially Cantrip Cascade, which comes with a paltry 3 charges out of the box.

Cantrip Cascade (5 SP): Cast each of your level 1 sorcery spells on each enemy in a 7 range cone; 3 charges. With Poison Sting, Magic Missile, and the spells and skills listed so far, each enemy will take physical and arcane damage, a -100 Poison Resistance debuff, and be poisoned and surrounded by 4 fae thorns. When cast on a dense clump of enemies, the entire area is clogged with thorns. Very helpful as later levels become more dense with powerful enemies. A great way to start a level so that enemies don't have a chance to focus on you before you get a chance to start spawning thorns.

Mystic Vision (3 SP): For 8 turns, all spells gain +5 range; 4 charges. Mostly used to buff Cantrip Cascade, which otherwise has a very limited range of 7. But longer range Poison Sting and Magic Missile is fun too. Remember to cast before entering a rift so that your first turn on the other side can be an extended-range Cantrip Cascade. Cantrip Cascade has a range upgrade, but it costs the same number of spell points for a smaller extension in range, so I prefer Mystic Vision even though it takes an additional turn to cast.

Void Beam (4 SP): Deal 25 arcane damage and destroy walls in a beam; 15 range, 7 charges. This will spawn thorns, but that's not the main reason to use it. It's just a good way to snipe gates, open up maze levels, and beat a path to Mordred when he teleports away. In later levels, having to break enemy hordes using thorn tactics alone is just too much of a pain. The build, while safe, can frankly be a little tedious to play and Void Beam allows you to avoid some annoying, drawn out levels.

Feel free to take Void Beam earlier in the build if you want. You'll be trading some core thorn power for the ability to quickly delete gates earlier in the realms.

Arcane Shield (4 SP): If you have no SH, gain 1 SH on casting an arcane spell. Being shielded is nice, and you're casting arcane spells all the time.

Paralyzing Venom (4 SP): Whenever an enemy takes poison damage, it has a 25% chance to be stunned for 1 turn. This is a big improvement on the build's ability to lock enemies down. Note that poisoned enemies will be stunned a quarter of the time from ongoing poison damage, while enemies that take multiple Venom Spit hits have a high probability of being stunned.

Teleport (5 SP): Note the extra 2 charges (from 1 to 3) from Void Lord. I typically take this in preparation for the Mordred fight; otherwise, I usually prefer direct combat upgrades. An upgraded Blink is also an option, but I've never tried.

These are relevant to the build, but aren't my main recommendations.

Void Dragons (4 SP): Void Dragons' breath weapon destroys walls. A good alternate option to break open levels and synergizes well with skills like Minion Shields and Cracklevoid. Since the dragons fly, they're also a help on chasm-heavy levels. I've taken this as an alternative to Arcane Combustion and Wolf (you can start Realm 2 on a spell point and take the dragons as your second spell), and it works fine, but it's just not my preference.

Spider Spawning (4 SP): Whenever an enemy dies to poison damage, summon a giant spider nearby. With your Thorns and Poison Sting dishing out poison damage, you can get a decent number of spiders. They just don't do enough to be worth the points, in my opinion.

Purestrike (5 SP): Whenever you or an ally deals physical damage to an enemy, if the source of that damage is shielded, redeal 50% of that damage as holy and 50% as arcane. Actually a hefty 2x increase in damage for your thorns once you have Minion Shields. But other choices are a priority in the early game, and Void Spikes / Cracklevoid are often more powerful later in the game, along with addressing some strategic weaknesses in the build. Note that even with Purestrike your thorns won't melee enemies with Physical immunity, which unfortunately removes a big reason why you'd want it in the first place.

Arch Sorceror (7 SP): Sorcery spells and skills get +2 charges, +7 damage, and +2 range. Nice buffs for the sorcery spells in the build, but not worth the points. The main damage output in the build is thorns, not sorceries.

Minion Regeneration (4 SP): All your minions gain 2 regen. Just not worth it for limited-duration thorns, and too expensive to be worth buffing your wolves.

Natural Vigor (4 SP): Your minions gain 25 physical, fire, ice and lightning resist. Good, just not good enough to make it a priority in the build.

Faestone (4 SP): Whenever you enter a new level, summon a fae stone nearby. The stone is stationary, has 120 hp and 20 physical damage melee attack. Whenever you cast an arcane spell, the stone teleports near the target and gains 1 SH. Whenever you cast a nature spell, the stone heals for 10 hp. Relevant to the mix of nature and arcane spells in the build, but I've never actually experimented with it because it just doesn't seem like it's worth the points.

Icy Vengeance (6 SP): Whenever your minion dies, deal ice damage equal to half its max hp to 3 enemies in a 5 tile radius. I've never actually tried this. It looks good, but it doesn't look sufficiently cost effective to replace anything else in the build.

Poison Immune enemies, including monster gates

Be sure to tap these with Poison Sting once you have Acidity to strip their immunity. This allows thorns outside of melee range to use Venom Spit on these enemies. Note that Poison Sting cannot strip Poison immunity from enemies with 100% Physical resistance, even with the Acidity upgrade. Note that Poison Sting also won't remove Poison resistance until after an enemy's shields are down.

Physical + Poison Immune enemies (ghosts)

Watch out for these. Your thorns cannot hurt them using their melee or Venom Spit attacks. These enemies can eat a lot of Magic Missiles, particularly if you don't have Arcane Combustion or don't use it effectively. Note that Arcane Combustion allows you to take out multiple ghosts with a single shot, but it also means killing a ghost adjacent to you with Magic Missile will blow up in your face. Note that witches spawn ghosts, so be careful around witch levels, especially early ones. The witch ghosts are temporary and don't do too much damage, so sometimes I just tank the hits until they disappear. You could always take an additional cantrip to kill ghosts, but in practice I don't like sparing even a single SP in the early game, and ghosts aren't as big of a problem once you have Void Spikes and they kill themselves attacking your thorns. Note that the stationary Tombstone enemy will summons a ghost near you every few turns. Sheesh. Finally, note that Greater Vampires turn into Vampiric Mists when they die, which have 12 HP (1 more than base Magic Missile damage), have physical and poison immunity, fly, and turn back into Greater Vampires if you leave them alone too long. They're a pain.

Arcane Immune enemies

Watch out for these later in the game when you start counting more on Arcane Combustion and Void Spikes to clear out hordes of enemies. Note that Void Fiends can summon large numbers of 75% Arcane Resist Void Imps. See my notes on Void Slimes below.

Troubler Gates

I skip levels with Troubler Gates. I don't even know if this build has particular difficulty with them. I prefer more stable and controlled situations and Troublers are the exact opposite of that. If you've ever struggled or died on a level with lots of Troublers, you know what I mean. But the build can handle a small number of them no problem.

Enemies that can teleport you or swap places with you

This build benefits from being able to stay put in a safe location surrounded by defensive thorns. Watch out for these enemies. You may have to use inventory items if you end up surrounded.

Gnomes

This build has no trouble with the notoriously pesky Gnomes (which have shields and summon thorns themselves). Just be careful to note which thorns are friendly and which are enemies.

Tanky Enemies

Single target DPS is not the build's strong point, but the thorns will constrict enemy movement, and eventually even high HP enemies will fall. Just be aware that it's going to take a few turns to knock that 600+ HP tank down, and make sure to strip its poison resistance using Poison Sting.

Enemies that can freeze, stun, petrify, or glassify you

Be very careful around these. In my experience, it's pretty easy to avoid taking too much damage using this build, as the enemies get continuously distracted, killed, or boxed out by thorns. But you can't spawn thorns if you're frozen by an Ice Dragon or petrified by a Cockatrice. Use the t key to check the range of any enemy with one of these capabilities. Avoid being in range without a good number of thorns on the map for defense and distraction. Zone these enemies out if at all possible so you're not in range of their attacks.

Enemies that can blind you

Note that this build is not going to work well if you're blinded. You won't be able to do much of anything but spawn thorns and wolves right next to you. Note that the Raven Mage has an ability that blinds you and all your minions for 3 turns.

Chain Lightning Aelfs

Note that these will be able to hit you and (up to) all of your thorns from long range, starting the chain on a nearby thorn. Void Spikes deals with them efficiently.

Bone Shamblers, Slimes, and Wormballs

Bone Shamblers can have hundreds of HP and split into two half-HP shamblers when they die. Slimes gain HP every turn and split into two slimes if they gain enough HP. Wormballs split into smaller wormballs when they die.

Your strategy with these enemies hinges heavily on whether you have Arcane Combustion. If you do, it can serve as AoE to take out swarms of the low-HP units created by these enemies, destroying higher HP versions in the process. Note that you will likely get caught in the blast as both enemies and minions trigger Arcane Combustion. If you don't have Arcane Combustion, high-HP bone shamblers are going to consume a lot of spell charges, and slimes may be difficult if you let them get out of control. Void Dragons can help by opening up the map and damaging lots of slimes in each breath attack. Note that Void Slimes have 100% arcane and poison resist and 50% physical resist. Consider avoiding Void Slimes altogether.

Idol of the Fickle

Decreases player spell and skill duration by 3. Be careful taking a level with these in it - your thorns will have considerably less duration.

Using Wolf

One of my favorite uses of Wolf in this build is to physically impede enemies from getting close to me. Thorns are sometimes undependable for this purpose, since they spawn on random tiles nearby the target of the spell that summons them. Drop a Wolf in a square adjacent to the wizard to keep enemies blocked from reaching you.

Chasm Levels with a mazelike layout/very few floor and wall tiles

The efficacy of the build goes down if there isn't space for thorns to spawn, and a lack of walls means enemies can rapidly converge and focus fire on your position. Walls can also be transformed into floor tiles by Arcane Combustion, Void Beam, etc. Watch out for these levels, even if the enemies don't look that powerful. You will be at a disadvantage compared to levels with more floor and/or wall tiles.

Open arena levels

Be careful not to get swarmed. Large numbers of powerful enemies can overwhelm your ability to spawn thorns to manage enemy movements. The ideal level for this build has at least some mazelike elements to keep enemies from advancing quickly on you in dense groups. On the other hand, Cantrip Cascade can sometimes clear out an arena quickly.

Entering a Realm

Early on, spawning thorns in your first few turns will distract enemies enough to keep you relatively safe. Note that enemy AI does not preferentially target the player if other targets are available - they just choose at random, even if the player is in melee range. Later on, cast Mystic Vision, enter the rift, spawn near a clump of enemies, and cast Cantrip Cascade to start things off with 14-20+ thorns and clear out a safe space from which to launch further attacks around the map.

Shrines

I don't know of any "killer" shrine for the build. The applicability of most shrines to the build should be self-explanatory. Note that Cantrip Cascade never hurts or kills anything, it only casts other spells that kill things. I won't pick anything up outside of the listed build just to use a shrine, with perhaps one exception: Icicle with Frozen Shrine (damage from spell or minions freezes for 2 turns, ice spells only) adds a 1 SP freezing capability to Cantrip Cascade.

Mordred / Realm 25

Not that hard if you have some potions, a good teleport capability, and 2-3 Golden Stopwatches to get out of dangerous situations when Mordred corrupts the map and brings in new enemies. Just treat him as any other high HP caster. It's especially good if he's near other enemies for a big Cantrip Cascade. In contrast, you might have to stall for a few turns if he teleports to an isolated floor tile surrounded by chasms. You won't be able to do much damage until he teleports or transforms the map into something more favorable for you. It's not a quick kill, but you can eventually wear him down.

Have fun using Thorn Garden!