Damage type

Every attack in NetHack has a defined damage type that determines how the attack of a monster or hero affects the target when it hits. This is distinct from the attack type, which determines how that attack makes contact with the target. Many damage types naturally deal hit point damage, and several have additional effects beyond that damage, which can include inflicting status properties on the target or affecting items in their open inventory—several do not deal hit point damage, and will instead apply different effects depending on the damage type.

Magic cancellation, resistance properties and certain types of items can negate the effects of some damage types, and the attacks of cancelled monsters with certain damage types will have no effect.

Damage types are defined within monattk.h in the source code.

Cancellation and damage types

If the attacker is cancelled, then several attack types are blocked, and most special damage types are blocked—cancellation is effective if either the attack type or the damage type are blocked. For example, if a dragon is cancelled, its breath attack cannot be used and will do no damage, regardless of the damage type.

These damage types are not blocked: ordinary physical damage, magic missile, disintegration, digestion, drain intelligence, illness, the Riders' special damage types, and the Amulet-stealing damage type.

Magic cancellation and damage types

Magic cancellation (not to be confused with cancellation) has a probability of blocking the effects of certain attack and damage types, and is only effective if the attack has both an eligible attack type and an eligible damage type. And even then, there is only a probability of blocking the attack.

These damage types are eligible for magic cancellation: fire, cold, sleep, shock, poison (versus strength, versus dexterity and versus constitution), slow, paralysis, drain life, drain energy, sticking, teleport, lycanthropy, sliming, and disenchanting.

List of damage types

A user has suggested improving this page or section as follows:

"Linkify the remaining unlinked attack types, creating articles where necessary."

Below is a list of damage types and their effects, as well as whether or not they are affected by cancellation or magic cancellation:

List of damage types

ID	Name	Blocked by	Effects	Example monsters
AD_PHYS	Physical damage	Armor (partial), Half physical damage (half)	Deals ordinary physical damage. The most common type.	jackal, hill giant
AD_MAGM	Magic missile	Magic resistance	A blast of missiles.	gray dragon, Angel
AD_FIRE	Fire	Fire resistance (HP damage)	May burn up scrolls, potions, spellbooks, and globs of green slime in the defender's inventory. Passive fire damage may burn the attacker's weapon. Burns away slime.	fire ant, red naga
AD_COLD	Cold	Cold resistance (HP damage)	May freeze and shatter potions in the defender's inventory.	winter wolf, freezing sphere
AD_SLEE	Sleep	Sleep resistance	No hit point damage. Puts the defender to sleep.	only homunculus, orange dragon, Nazgul
AD_DISN	Disintegration	Disintegration resistance	No hit point damage. This disintegrates the defenders's worn shield if applicable, or disintegrates the defender's worn cloak and body armor if applicable, and otherwise causes instadeath.	only black dragon
AD_ELEC	Shock	Shock resistance (HP damage)	May explode wands and rings in inventory.	blue dragon, grid bug
AD_DRST	Poison vs strength	Poison resistance	The most common type of poison. It may lower strength, and has a chance of causing instadeath. Against monsters, it may cause an instadeath.	green dragon, soldier ant, snake
AD_ACID	Acid	Acid resistance (HP damage)	On passive attacks, this may also corrode worn or wielded items.	acid blob, yellow dragon, ochre jelly
AD_BLND	Blind		No hit point damage. Blinds the defender. For some attack types, cancelling the attacker blocks this damage type; for others, a blindfold or certain other equipment blocks this damage type.	yellow light, dust vortex, Archon
AD_STUN	Stun		Stuns the defender.	only yellow mold, abbot, Baalzebub
AD_SLOW	Slow		Deals no extra hit point damage and slows the defender.	only skeleton, shade
AD_PLYS	Paralysis	Free action	Deals no extra hit point damage and can paralyze the defender.	floating eye, gelatinous cube, shade
AD_DRLI	Drain life	Drain resistance	Drains a level from the defender. May cause instadeath if the defender is drained below level 1.	vampire, barrow wight, wraith
AD_DREN	Drain energy		No hit point damage. Against the hero, this drains power, and then drains maximum power if their current power is 0. Magic cancellation blocks this attack unless the hero is engulfed. Against a monster, it prevents them from using magical attacks or breath weapons for several turns.	only energy vortex
AD_LEGS	Wounded legs		Certain boots have a probability of blocking HP damage. Against the hero, it causes wounded legs. Against a monster, it deals ordinary physical damage.	only xan
AD_STON (touch attack)	Stoning	stoning resistance	No hit point damage. Delayed instadeath by stoning.	only chickatrice, cockatrice
AD_STON (passive attack)	Stoning	stoning resistance, gloves (if punching) or boots (if kicking)	No hit point damage. Instadeath by stoning.	only chickatrice, cockatrice
AD_STON (gaze attack)	Stoning	stoning resistance, blindness, or reflection	No hit point damage. Instadeath by stoning.	only Medusa
AD_STCK	Sticking		Against the hero, this deals no additional hit point damage, but causes them to stick to the attacker, and prevents them from moving off their current square until the attacker dies or otherwise releases them. Against a monster, it deals ordinary physical damage.	only lichen, violet fungus, large mimic, giant mimic
AD_SGLD	Steal gold		The attacker steals some or all of the defender's gold, then teleports if the theft is successful. Against the hero, the attacker may also snatch the gold that the hero was standing on.	only leprechaun
AD_SITM	Steal one item		Deals no hit point damage and steals one item from the defender, followed by the attacker teleporting and/or fleeing.	only monkey, nymph
AD_SEDU	Steal multiple items		Deals no hit point damage and steals multiple items. Not to be confused with AD_SSEX or AD_SAMU.	only nymph
AD_TLPT	Teleport		The defender is teleported to a random tile on this level, subject to teleport control, unless the level is no-teleport. HP damage is limited so that it will not kill the defender.	only quantum mechanic
AD_RUST	Rust		Causes a random piece of worn armor to rust, which may fail if it is blessed, rustproof or not rustable. As a passive attack, it tries to rust the gear that made contact. Instadeath for iron golems.	only gray ooze, rust monster
AD_CONF	Confusion		Deals no hit point damage and confuses the defender.	only umber hulk, Yeenoghu
AD_DGST	Digestion	Slow digestion	Against the hero, it engulfs them and starts a delayed instadeath. Against a monster, it is an immediate instadeath if they are small enough, and otherwise deals physical damage.	only trapper, lurker above, purple worm
AD_HEAL	Healing		Against the hero, it deals physical damage unless they are wearing no armor and wielding no weapon, in which case multiple positive effects occur, including healing the hero and raising their maximum HP. Against a monster, it deals ordinary physical damage.	only nurse
AD_WRAP	holding / Drowning	Greased armor or oilskin cloak	Against the hero, it grabs on the first hit, the attacker swings itself around the hero. On the second hit, if the attacker is in water, the hero drowns in an instadeath. Against a monster: damage is ordinary physical.	eels, kraken, python
AD_WERE	Lycanthropy	Protection from shape changers or wielding Werebane	Against the hero, it causes lycanthropy. Against a monster, it deals ordinary physical damage.	only werecreatures
AD_DRDX	Poison vs dexterity	Poison resistance	Against the hero, it may lower dexterity, and has a chance of causing instadeath. Against a monster, it deals HP damage and may cause instadeath.	only quasit
AD_DRCO	Poison vs constitution	Poison resistance	Against the hero, it may lower constitution, may cause instadeath. Against a monster, it deals HP damage and may cause instadeath.	only rabid rat
AD_DRIN	Drain intelligence	Worn helm (7⁄8 of the time), greased worn helm (always, but may wear off 1⁄2 of the time)	Against the hero, it lowers intelligence if not blocked, can additionally cause amnesia, and causes an instadeath if their intelligence is drained enough. Against a monster, it deals HP damage, and deals extra damage if the defender is not mindless.	only mind flayer, master mind flayer
AD_DISE	Illness	Immunity to sickness	Against the hero, it causes illness, which may cause delayed instadeath. Against a monster, it has no effect.	only Scorpius, Juiblex, Demogorgon
AD_DCAY	Rot		Against the hero and monsters, it rots a random piece of worn armor; as a passive attack, it rots the item that made contact. Instadeath for wood golems and leather golems.	only brown pudding
AD_SSEX	Seduction		No hit point damage. Against the hero, it initiates a seduction attack; this is changed to AD_DRLI if sysconf option SEDUCE is not set. May cause an indirect instadeath under certain circumstances by removing certain armor or rings. Against a monster, it behaves the same as a normal item-stealing attack.	only incubus and succubus
AD_HALU	Hallucination	blindness or hallucination resistance	No hit point damage. Against the hero, it causes hallucination. Against a monster, it causes confusion.	only black light
AD_DETH	Death's special attack	Magic resistance (instadeath)	Against the hero, it deals damage to both current and maximum hit points, and may cause an instadeath. Against a monster, it has no effect.	only Death
AD_PEST	Pestilence's special attack	Immunity to sickness	Against the hero, it causes illness, which may cause a delayed instadeath. Against a monster, it has no effect.	only Pestilence
AD_FAMN	Famine's special attack		Against the hero, it drains nutrition, but not if the hero is already fainting, and abuses constitution. Against a monster, it has no effect.	only Famine
AD_SLIM	Sliming	Unchanging	Against the hero, it may cause delayed instadeath by sliming. Against a monster, it may cause an instant transformation into a green slime.	only green slime
AD_ENCH	Disenchanting		Against the hero, it attempts to disenchant one item. As a passive attack, it disenchants the item that made contact. Against a monster, it deals ordinary physical damage.	only disenchanter
AD_CORR	Corrosion		Corrodes one item. As a passive attack, it corrodes the item that made contact.	only black pudding
AD_CLRC	Clerical spell		Against the hero, the attacker casts a clerical spell appropriate to the attacker's level. Against a monster, it has no effect.	aligned priest, high priest, Master Kaen
AD_SPEL	Mage spell		Against the hero, the attacker casts a mage spell appropriate to the attacker's level, which may include the touch of death. Against a monster, it has no effect.	lich, orc shaman, Wizard of Yendor
AD_RBRE	Random breath weapon		This damage type resolves to a random damage type between AD_MAGM and AD_ACID.	only the Chromatic Dragon
AD_SAMU	Steal the Amulet		Against the hero, the attacker steals a valuable item such as the Amulet of Yendor, any other unique item, or any quest artifact. Against a monster, it has no effect.	only quest nemeses, the Wizard of Yendor
AD_CURS	Steal intrinsic		Against the hero, it removes a random intrinsic from them. Against a monster, it may cancel the defender. Instadeath for clay golems.	only gremlin

The following information pertains to an upcoming version (3.7.0). If this version is now released, please verify that the information below is still accurate, then update the page to incorporate it.

Extrinsic properties that resist a given damage type protect the target's inventory from that damage ⁹⁹⁄₁₀₀ of the time, and a worn dwarvish cloak prevents inventory damage from fire and cold attacks ⁹⁄₁₀ of the time.

Per commit 017a8687, the illness attack types and the attack types unique to each Rider are made functional in monster-to-monster combat.

History

In NetHack 3.4.3 and previous versions, including some variants based on those versions, magic cancellation has higher probabilities for blocking the effects of certain damage types - in particular, MC3 blocks ⁴⁹⁄₅₀ or 98% of damage types that it affects, making it an incredibly desirable and reliable property to have.

NetHack 3.6.0 introduces the current magic cancellation system and applies the following changes to damage types:

• Half physical damage blocks more instances of physical damage than it did in NetHack 3.4.3.
• Grease protects against all types of erosion.
• Passive fire damage may burn the attacker's weapon.
• Passive attacks no longer erode armor covered by other armor.
• AD_DREN implemented, actually draining energy (energy vortices).

NetHack 3.6.1 applies the following changes to damage types:

• The AD_SAMU damage type is given the ability to take any quest artifact, rather than just the one corresponding to the hero's role.

NetHack 3.6.2 applies the following changes to damage types:

• If hero survives sliming via lifesaving, hero continues adventuring in slime form.
• If AD_TLPT succeeds in teleporting, hit point damage is limited so that defender will not die from hit point loss.

NetHack 3.6.3 applies the following changes to damage types:

• AD_LEGS no longer fails to deal damage against a target that is flying, levitating or riding as in previous versions.