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 higher the value, the better.
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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.
  
The most common way to improve your AC is by wearing [[armour]]. Heavier and higher-AC [[body armour]] (and body armour alone) comes at the cost of [[Encumbrance rating|encumbrance]], which reduces [[EV]], [[spell failure|spell success]] rates, and [[stealth]]. Other pieces of gear, especially [[artefact]]s, may also increase your AC, and magical spells may temporarily boost it.  
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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==
In general, 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 defense in other games, such as most [[spell]] magic and elemental attacks. However, this is not always precisely true. 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.
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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.
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For details on how AC is calculated, see [[AC calculations]].
  
 
===Guaranteed Damage Reduction===
 
===Guaranteed Damage Reduction===
 
''Main Article: [[GDR]]''
 
''Main Article: [[GDR]]''
  
When taking physical damage in melee, 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.
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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.
  
 
==List of Damage that ignores AC==
 
==List of Damage that ignores AC==
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*[[Smite]].
 
*[[Smite]].
 
*[[Damnation]].
 
*[[Damnation]].
*'''Status Effects''': [[poison]], [[sticky flame]], [[flay]].
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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).
*'''Weapon [[brand]] damage''': includes [[attack flavour]]s.
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*'''Status effects''': [[poison]], [[sticky flame]], [[flay]].
** Note that weapon brand damage is a percentage of AC-reduced damage in the first place.
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*'''Hex effects''': [[Pain]] / [[Necrotise]], [[Wand of mindburst|Mindburst]], [[Anguish]], [[Agony]]
** Some attack flavours require a physical AC attack to deal damage to apply, though are not influenced by AC themselves.  
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*'''Weapon [[brand]] damage''' and '''monster [[attack flavour]]s'''.
*'''Specific spells''': [[Freeze]], [[Vampiric Draining]], [[Static Discharge]], [[Frozen Ramparts]], [[Ozocubu's Refrigeration]].
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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).
 
**The chilling blast [[draconian breath attack|breath attack]] of a [[Draconian_(monster)|white draconian]].
 
**The chilling blast [[draconian breath attack|breath attack]] of a [[Draconian_(monster)|white draconian]].
*'''Hex effects''': [[Pain]], [[Anguish]]
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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.
  
 
[[Category:Stats]]
 
[[Category:Stats]]
 
[[Category:Game mechanics]]
 
[[Category:Game mechanics]]
 
[[Category:Defence]]
 
[[Category:Defence]]
[[Category:Crystal Ball Articles]]
 

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