Raw details on damage types can be found in tome-x.y.z.team/data/damage_types.lua
Tales of Maj'Eyal uses a multitude of damage types. Generally speaking, damage types are grouped along a few loose sets of types, some of which have secondary effects on damaging a mob. Damage from different types can be reduced by resistances.
This information is directly from the comments in the damage_types.LUA file and consists mostly of comments in the code as well as some additional information such as death messages.
physical: Caused by regular melee and ranged attacks by weapons, and physical attacks by monsters. Stone magic talents and Wyrmic Sand drake aspect talents also cause physical damage. Most common damage type early in the game.
- Death Message: "battered", "bludgeoned", "sliced", "maimed", "raked", "bled", "impaled", "dissected", "disembowelled", "decapitated", "stabbed", "pierced", "torn limb from limb", "crushed", "shattered", "smashed", "cleaved", "swiped", "struck", "mutilated", "tortured", "skewered", "squished", "mauled", "chopped into tiny pieces", "splattered", "ground", "minced", "punctured", "hacked apart", "eviscerated".
arcane: Arcane is basic (usually) un-resistable damage. Caused by pure magic skills and magic-using monsters. Category Arcane talents cause arcane damage. Difficult to find resistances to.
- Death Message: "blasted", "energised", "mana-torn", "dweomered", "imploded".
Fire: Caused by fire mages (pyromancers), Wyrmics using fire drake talents, and fire-breathing or using monsters. One of the most common types of damage.
- Death Message: "burnt", "scorched", "blazed", "roasted", "flamed", "fried", "combusted", "toasted", "slowly cooked", "boiled".
cold: Caused by ice mages (cyromancers), Wyrmics using cold drake talents, and cold-breathing or using monsters. Includes ice giants and Rantha the Worm.
- Death Message: "frozen", "chilled", "iced", "cooled", "frozen and shattered into a million little shards".
lightning: used by lightning mages, Wyrmics using storm drake talents, and lightning-using monsters. This include air elementals and Urkis. Keeping a few extra lightning resist items in reserve is a good idea.
- Death Message: "electrocuted", "shocked", "bolted", "volted", "amped", "zapped".
acid: Caused by some nature talents, Wyrmics using acid drake talents, and acid-based monsters. This includes jellies and blobs. Acid damage is very often applied as damage over time instead of one single shot of damage.
- Death Message: "dissolved", "corroded", "scalded", "melted".
Nature & Blight: opposing damage types
Nature: Caused by poisons, special animal attacks, some Wild Gifts, and some mindstars.
- Death Message: "slimed", "splurged", "treehugged", "naturalised".
- Death Message: "diseased", "poxed", "infected", "plagued", "debilitated by noxious blight before falling", "fouled", "tainted".
Light & Darkness
- Death Message: "radiated", "seared", "purified", "sun baked", "jerkied", "tanned".
Darkness: Caused by some talents from the Afflicted classes, as well as Anorithil (category Star Fury) and from darkness-themed monsters. Can also cause tiles to become dark. Necromancers start with darkness spells and get access to more of this type if they become a Lich.
- Death Message: "shadowed", "darkened", "swallowed by the void".
Mind & Temporal
Mind: Most uses of this have their damage effected by mental save and do not trigger cross tiers, ie, melee items. Mind damage is caused by psionic skills and monsters that use mental attacks. Many of the talents from the Afflicted classes cause mind damage. Also caused by mindstars and weapons with the 'projection' ego.
- Death Message: "psyched", "mentally tortured", "mindraped".
Temporal: Caused by Chronomancer talents and from time-themed monsters. Uncommon before the Far East, except for in the Temporal Rift found in Daikara. There is a temporal zone in the Embers campaign called Pocket of Distorted Time.
- Death Message: "timewarped", "temporally distorted", "spaghettified across the whole of space and time", "paradoxed", "replaced by a time clone (and no one ever knew the difference)", "grandfathered", "time dilated".
Special Damage Types
Special damage types have an additional effect or effects, or are unusual because they aren't covered by the usual types of resistance.
Acid Blind: Acid damage and chance to Blind.
Arcane Silence: Arcane damage and silences the target for 3(?) turns.
Bleed: Physical damage as DOT.
Blinding Light: Light damage and 25% chance to Blind.
Corrupted Blood: inflicts Blight damage on the target, and may trigger a random lesser disease (Blight) debuff on the target.
Cosmetic: no damage occurs, the damage type is purely cosmetic. It can exist on things, but doesn't do anything though. Death Message: cosmeticed.
Dazing Lightning: "Lightning damage + daze chance". Does lightning damage with a 25% chance to daze unless otherwise stated.
Draining Blight: inflicts Blight damage on the target, and restores half of the damage dealt.
Disarming Acid: acid damage with a 25% chance to disarm.
DreamForge: damage is half Fire and half Mind. Can do knockback, and may be susceptible to saves.
Fire Burn: inflicts Fire damage and burns the target over multiple turns.
Flameshock: Fire DOT + Stun. Does fire damage over 4 turns and applies the Burning Shock debuff.
Holy Light: Holy light, damage demon/undead; heal others. Damages demons and undead while healing everything else.
Ice: Cold damage + freeze chance. Does cold damage with a 25% chance to iceblock the enemy for 2 turns with an iceblock health of hp=70+dam*1.5.
Insidious Poison: Poison (nature damage) and reduces any healing of the target by at least 10% over several turns.
Lightburn: like Fire burn, but with Light.
Manaburn: if target has mana, vim, positive, or negative, removes some and deals proportional arcane damage. Won't reduce them below zero and does nothing if target has zero.
Nature Slow: AKA Slime, Nature damage and inflict a 15% Slow over multiple turns.
Poison: Nature damage over time.
Purging Blight: Retch: heal undead; damage living. Damages living while healing undead, found on Retch.
Shadowflame: Darkness + Fire. Does 50% darkness and 50% fire damage.
slowing ice: Cold damage + freeze chance + 20% slow. Does cold damage with a 20% chance to slow and a 25% chance to iceblock the enemy for 2 turns with an iceblock health of hp=70+dam*1.5.
Spydric Poison: Spydric poison: prevents movement. Very special, does not have a power check. Does poison DOT (nature damage) but pins an enemy in place.
Temporal Darkness: damage is half Temporal and half Darkness; may be referred to as void.