Difference between revisions of "Armour class"

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When something injures you, your '''Armour class''' (often abbreviated to '''AC''') reduces the amount of damage you suffer. The most common way to improve your AC is by wearing body [[armour]], gloves, boots, cloaks, and head gear. Other pieces of gear, especially [[artefact]]s, may also increase your AC, and magical spells may temporarily boost it too. While heavier armour provides superior protection, it also reduces your [[Evasion]], hinders spellcasting, and causes you to occasionally miss attacks unless you have sufficient [[Armour (skill)|Armour skill]] to offset its penalties.
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{{version030}}
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When something injures you, your '''armour class''' (often abbreviated to '''AC''') reduces the amount of damage you suffer. The higher the value, the better.
  
Armour can be enchanted with [[scroll of enchant armour|scrolls of enchant armour]] to grant bonus AC.
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The most common way to improve your AC is by wearing [[armour]]. Wearing heavier [[body armour]] provides more AC, but comes at the cost of [[encumbrance]] - reducing [[EV]], [[spell failure|spell success]] rates, and [[stealth]]. Other types of armour, like [[helmet]]s and [[boots]], provide AC with no penalty.
  
==AC damage reduction==
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==Useful Info==
AC reduces the damage of attacks susceptible to AC by an absolute value between 0 and your current AC value: in other words, an AC of 10 will reduce damage by a random number between 0 and 10. However, this is not strictly true, as there is always a minimum [[guaranteed damage reduction]] based on your body armour's base AC. See the [[AC calculations]] page for more details.
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AC reduces the damage of attacks by an absolute value between 0 and your current AC value. An AC of 10 will reduce damage by a random number between 0 and 10. This applies to damage that would traditionally ignore armour in other games, such as [[spell]] magic.
  
==List of attacks or sources of damage which are not reduced by AC==
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<code>BEAM_ELEC</code> damage (such as from [[Shock]] or [[Lightning Bolt]]) ignores half of the target's AC. <code>BEAM_FRAG</code> damage (such as from [[Sandblast]] or a [[tin of tremorstones]]) is affected three times as much by AC.
*Special damage caused by weapon [[brand]]s, [[attack flavour]]s (except [[pure fire]] which is is used by [[fire elemental]]s and [[fire vortexes]]) and [[magical staves]] (except the [[staff of earth]] and the [[rod of striking]]).
 
*The followings [[status effects]]: [[poison]], [[rotting]], [[bleeding]].
 
*The following spells ignore AC: [[Freeze]], [[Pain]], [[Vampiric Draining]], [[Static Discharge]], [[Sticky flame]], [[Agony]] and [[Ozocubu's Refrigeration]].
 
*Also, the following monster spells, abilities or scrolls: [[Torment]], [[Holy Word]], [[Smite]], [[Hellfire]] and [[Draconian_(monster)|White Draconian]]'s chilling blast.
 
  
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For details on how AC is calculated, see [[AC calculations]].
  
[[Category:Stats]] [[Category:Game mechanics]][[Category:Defence]]
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===Guaranteed Damage Reduction===
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''Main Article: [[GDR]]''
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When taking physical damage from a melee attack, guaranteed damage reduction will improve AC rolls. GDR% is equal to <code>16*(AC)^1/4</code>. If GDR is applied, the minimum possible AC roll will equal (damage*GDR%) or (AC/2), whichever is lower. GDR only applies to melee, ranged weapon, and throwing attacks. Only the player benefits from GDR.
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==List of Damage that ignores AC==
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*[[Torment]] and [[Holy Word]].
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*[[Smite]].
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*[[Damnation]].
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*'''Shared damage''' from [[Anguish]], [[Injury Mirror]], [[Injury Bond]], [[Uskayaw#Given Abilities|Pain Bond]], or [[spectral weapon]]s (uses the original target's AC instead).
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*'''Status effects''': [[poison]], [[sticky flame]], [[flay]].
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*'''Hex effects''': [[Pain]] / [[Necrotise]], [[Wand of mindburst|Mindburst]], [[Anguish]], [[Agony]]
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*'''Weapon [[brand]] damage''' and '''monster [[attack flavour]]s'''.
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** Note that weapon brand damage is often a percentage of AC-reduced damage in the first place.
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** Some monster attack flavours require a physical, AC-checking attack to deal damage to apply, though the attack flavour itself is not influenced by AC.
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*'''Specific spells''': [[Freeze]], [[Vampiric Draining]], [[Static Discharge]], [[Ignite Poison]], [[Dispel Undead]] / [[Dispel Undead Range]], [[Lee's Rapid Deconstruction]] (directly on a monster).
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**The chilling blast [[draconian breath attack|breath attack]] of a [[Draconian_(monster)|white draconian]].
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==History==
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*Prior to [[0.29]], [[Frozen Ramparts]] and [[Ozocubu's Refrigeration]] ignored AC.
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*Prior to [[0.26]], [[Irradiate]] ignored AC.
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[[Category:Stats]]
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[[Category:Game mechanics]]
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[[Category:Defence]]

Latest revision as of 11:14, 15 January 2024

Version 0.30: This article may not be up to date for the latest stable release of Crawl.

When something injures you, your armour class (often abbreviated to AC) reduces the amount of damage you suffer. The higher the value, the better.

The most common way to improve your AC is by wearing armour. Wearing heavier body armour provides more AC, but comes at the cost of encumbrance - reducing EV, spell success rates, and stealth. Other types of armour, like helmets and boots, provide AC with no penalty.

Useful Info

AC reduces the damage of attacks by an absolute value between 0 and your current AC value. An AC of 10 will reduce damage by a random number between 0 and 10. This applies to damage that would traditionally ignore armour in other games, such as spell magic.

BEAM_ELEC damage (such as from Shock or Lightning Bolt) ignores half of the target's AC. BEAM_FRAG damage (such as from Sandblast or a tin of tremorstones) is affected three times as much by AC.

For details on how AC is calculated, see AC calculations.

Guaranteed Damage Reduction

Main Article: GDR

When taking physical damage from a melee attack, guaranteed damage reduction will improve AC rolls. GDR% is equal to 16*(AC)^1/4. If GDR is applied, the minimum possible AC roll will equal (damage*GDR%) or (AC/2), whichever is lower. GDR only applies to melee, ranged weapon, and throwing attacks. Only the player benefits from GDR.

List of Damage that ignores AC

History