Every attack in NetHack has a defined damage type. This determines how the attack affects the target when it hits (as opposed to attack type, which determines how the attack makes contact with the target). There are many damage types and many effects for the wide assortment of monsters in NetHack. They are defined in monattk.h and used to specify monster attacks in monst.c.
Many damage types actually cause no HP damage; instead, the damage dice are used for the duration of an effect. However, the code is often inconsistent with when this applies.
Combining some attack types with certain damage types may lead to some unexpected effects. For example, giving a monster a weapon attack with a blinding damage type will cause it to blind the player as intended when the weapon hits, but it will not actually deal any damage.
Many damage types' effects can be negated through magic cancellation, but only if the attack is of an appropriate type. For these and most other damage types, the effect will also be negated if the monster is cancelled.
List of damage types
|Symbol||Damage type||HP damage?||MC prevents?||Effects||Example monsters|
|AD_PHYS||Physical||Yes||No||The most common sort. Half physical damage halves any damage of this type.||jackal, hill giant|
|AD_MAGM||Magic missiles||Yes||No||A blast of missiles. Player-style magic resistance negates this damage. All monsters that have an attack with this damage type act as if they have player-style magic resistance innately.||only gray dragons, Angels, Yeenoghu, the Oracle|
|AD_FIRE||Fire damage||Yes||Yes||Fire resistance negates this damage. It may also burn up scrolls, potions, and spellbooks in inventory.||fire ant, red naga|
|AD_COLD||Cold damage||Yes||Yes||Cold resistance negates this damage. It may also freeze and shatter potions in inventory.||winter wolf, freezing sphere|
|AD_SLEE||Sleeping||No||Yes||Sleep resistance prevents being put to sleep.||only homunculus, orange dragon, Nazgul|
|AD_DISN||Disintegrating / death rays||No ||No||Disintegrates, starting with armor but eventually instakilling. Death magic from the wand of death and finger of death spell also uses this damage type.||only black dragon|
|AD_ELEC||Shock damage||Yes||Yes||Shock resistance negates this damage. It may also explode wands and rings in inventory.||blue dragon, grid bug|
|AD_DRST||Poisoning, harming strength||Yes||Yes||Most common type of poison. In addition to increased HP damage, also lowers strength. May instakill non-resistant. Poison resistance negates all HP and strength damage. On monsters, all forms of poison are the same.||green dragon, soldier ant, snake|
|AD_ACID||Acid damage||Yes||No||Acid resistance negates this damage. On passive attacks only, it may also corrode worn or wielded items.||acid blob, yellow dragon, ochre jelly|
|AD_BLND||Blinding||No||No||Causes the target to become blinded. Depending on the attack type, various pieces of equipment may block this attack, such as a visored helm preventing blinding from ravens and spat venom.||yellow light, dust vortex, Archon|
|AD_STUN||Stunning||No||No||Causes the target to become stunned and stagger.||only yellow mold, abbot, Baalzebub|
|AD_SLOW||Slowing||No||Yes||Slows the target down. On the player, this removes intrinsic speed or reduces the player to slow speed. On monsters, this reduces permanent speed to 2/3 of its normal value.||only skeleton, shade|
|AD_PLYS||Paralyzing||No||Yes||Paralyzes the target. Free action negates this.||floating eye, gelatinous cube, shade|
|AD_DRLI||Draining life||Yes ||Yes||Drains a level from the target. Drain resistance negates this.||vampire, barrow wight, wraith|
|AD_DREN||Drain energy||Yes ||Yes||Mostly the same effects as an anti-magic field. On the player, this will drain Pw, and maximum Pw if current Pw is 0. However, unlike an anti-magic field, this will cause HP damage if maximum Pw is 0. Happens only 25% of the time.||only energy vortex|
|AD_LEGS||Wounding legs||Yes||No||Causes wounded legs to the player. Against monsters, it counts as physical damage.||only xan|
|AD_STON||Petrifying||No||No||Attempts to start a slow petrification process, subject to the 10% chance of hissing. However, if the attack type is AT_GAZE (Medusa), the petrification is instantaneous.||only chickatrice, cockatrice, Medusa|
|AD_STCK||Sticking||No||Yes||Causes the target to be stuck to the attacking monster and unable to move from that space until the monster is killed or otherwise releases them.||only lichen, violet fungus, large and giant mimics|
|AD_SGLD||Stealing gold||Yes||No||If the target is carrying any gold, steal some or all of it, or else snatch some gold that the player is standing on (this only works against the player).||only leprechaun|
|AD_SITM||Stealing one item||No||No||Steals a single item from the target. Monsters that steal will then flee; animals will try to run away, all other monsters will try to teleport away. Nymphs may cause you to take off a piece of armor, immobilizing you for several turns, and steal extra items for each turn you are immobilized.||only monkey, nymph|
|AD_SEDU||Charming, stealing multiple items||No||No||Currently the same as AD_SITM. The source calls this attack "seduction", but it is not the same damage type as the better known seduction type AD_SSEX.||only nymph|
|AD_TLPT||Teleporting||Yes||Yes||The target randomly teleports somewhere else on the level, subject to teleport control, unless the level is no-teleport.||only quantum mechanic|
|AD_RUST||Rusting||Yes||No||Causes a random piece of worn armor to rust, which may fail if it is blessed, rustproof, or not rustable. As a passive attack, tries to rust the gear that made contact. Instakills iron golems.||only gray ooze, rust monster|
|AD_CONF||Confusing||No||No||Confuses the target.||only umber hulk, Yeenoghu|
|AD_DGST||Digesting||Yes ||No||Only works when engulfing. Since monster engulfing is not implemented, when most monsters are digested, they will die instantly.||only trapper, lurker above, purple worm|
|AD_HEAL||Healing||Yes ||No||Against monsters (always) and the player (in most situations), damage is converted to physical. However, if the player is naked and wielding no weapon, heals the player by 1d7 points, cures sickness, and may increase maximum HP, exercise Strength, and exercise Constitution. This may cause the attacker to disappear or flee. Additionally, if the player is a Healer, the attacker will never deal damage even if they have weapons and armor equipped.||only nurse|
|AD_WRAP||Wrapping / Drowning||Yes||No||If the target is not already stuck to the attacker, the attacker grabs or swings itself around the target, making the target stuck to the attacker like the AD_STCK effect. If the target was already stuck and the attacker is in water, the target is drowned. Otherwise, the attacker is dealt crushing damage. This has no effect in monster-versus-monster combat.||eels, kraken, python|
|AD_WERE||Lycanthropy||Yes||Yes||On monsters, this is just converted into physical damage. On the player, it inflicts lycanthropy.||only wererat, werejackal, werewolf|
|AD_DRDX||Poisoning that harms Dexterity||Yes||Yes||Increased HP damage, lowers player's dexterity, may instakill. Poison resistance negates all effects.||only quasit|
|AD_DRCO||Poisoning that harms Constitution||Yes||Yes||Increased HP damage, lowers player's constitution, may instakill. Poison resistance negates all effects.||only rabid rat|
|AD_DRIN||Draining intelligence||Yes||No||Assumed to be tentacle brain-sucking by the code. No effect on headless monsters. Wearing a greased helm will apply the HP damage but no further effect; a non-greased helm will also do this 7/8 of the time. Should the attack succeed, the target's brains will be eaten; the player loses Int and suffers amnesia, whereas monsters take an extra 1d10 damage.||only mind flayer, master mind flayer|
|AD_DISE||Causing disease||No||No||The player is made (more) ill. No effect on monsters.||only Scorpius, Juiblex, Demogorgon|
|AD_DCAY||Rotting||Yes||No||Attempts to rot a random piece of worn armor. As a passive attack, tries to rot the gear that made contact. Instakills wood golems and leather golems.||only brown pudding|
|AD_SSEX||Seducing||No||No||For monsters, or if the SEDUCE system option is off, behaves identically to the AD_SITM and AD_SEDU item-stealing attacks. Otherwise, on the player only, initiates a seduction routine, which has various effects.||only incubus and succubus|
|AD_HALU||Hallucinating]||No||No||Makes the player start hallucinating. Monster hallucination is not implemented, so monsters become confused instead.||only black light|
|AD_DETH||Death's special attack||Yes ||No||Special attack: 15% chance of an instadeath unless you have player-style magic resistance, 30% chance of no effect, and 65% chance of dealing all of its damage to maximum HP in addition to current HP.||only Death|
|AD_PEST||Pestilence's special attack||Yes||No||Special attack: is basically a disease attack that also deals its full complement of HP damage.||only Pestilence|
|AD_FAMN||Famine's special attack||Yes||No||Special attack: makes you hungrier by 1d40 + 40 points unless you are fainted from lack of food, abuse Constitution, and also deal its full complement of HP damage.||only Famine|
|AD_SLIM||Sliming||Yes ||Yes||If the target is already a green slime, incorporeal, flaming, or has unchanging, it does not start to turn to slime; monsters will still take damage from this but not the player. Other monsters have a 25% chance of turning into a green slime instantly and a 75% chance of taking the damage with no further effect. The player will both take damage and start turning to slime with 10 turns to go.||only green slime|
|AD_ENCH||Disenchanting||Yes||Yes||On the player, disenchant a piece of gear (if a passive attack, disenchant the gear that made contact.) Monster disenchanting is not implemented, so monsters just take it as physical damage.||only disenchanter|
|AD_CORR||Corroding items||Yes||No||Attempts to corrode a random piece of worn armor. If a passive attack, attempt to corrode the gear that made contact.||only black pudding|
|AD_CLRC||Clerical spell||N/A||No||Casts a random clerical spell appropriate to the caster's level. No effect when the player is the attacker.||aligned priest, high priest, Master Kaen|
|AD_SPEL||Arcane spell||N/A||No||Casts a random mage spell appropriate to the caster's level. The player can never cast monster spells, so it has no effect when the player is the attacker.||lich, orc shaman, Wizard of Yendor|
|AD_RBRE||Random breath weapon||N/A||N/A||Not actually a damage type. When a monster attacks with AT_BREA and AD_RBRE (the Chromatic Dragon is currently the only such monster), it will set the damage type, and thus the type of breath, to a random damage type between AD_MAGM and AD_ACID.||only the Chromatic Dragon|
|AD_SAMU||Stealing the Amulet||Yes||No||No effect on monsters at all. On the player, 5% chance of stealing a valuable item from inventory, otherwise no effect. Items are stolen in the preferred order of: any quest artifact, the Amulet of Yendor, the Bell of Opening, the Book of the Dead, and the Candelabrum of Invocation.||quest nemeses, demon lords, the Wizard of Yendor|
|AD_CURS||Stealing intrinsic||Yes||No||If the attacker isn't a gremlin or it isn't night, no additional effect. On the player, attempts to remove a random intrinsic. On monsters, 10% of the time, attempts to cancel the monster. Instakills clay golems if the attack hits, including when the player is one.||only gremlin|
- Death and disintegration are all-or-nothing effects, however, and cause instadeath if they hit.
- Lost levels decrease maximum HP, and current HP along with it.
- Only if maximum Pw is 0.
- Also is timed; if the timer runs out the damage is set to current HP.
- Only when wielding a weapon or wearing armor.
- According to code comments, the name stands for "succubus seduction (extended)", but that's probably just a convenient excuse.
- This attack will drain current and maximum HP at the same rate.
- Only if the player is immune to sliming.