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.
 
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 failure|spell success]] rates, and [[stealth]]. Other types of armour, like [[helmet]]s and [[boot]]s, provide AC with no penalty.
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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.
  
 
==Useful Info==
 
==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, like [[spell]] magic.
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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.
  
 
<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.
 
<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 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 attacks.
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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.
 
 
==Calculating AC Value==
 
First, the AC from worn armour is equal to:<ref>{{source ref|0.28.0|player.cc|5691}}</ref>
 
 
 
  (base AC) * (Armour skill / 22 + 1) rounded down
 
 
 
Where "base AC" equals the ''sum'' of base AC from every worn armour (this excludes armour [[enchant]]ment). Rounding does not occur until all armour pieces have been calculated. Overall, Armour skill provides roughly +4.5% base AC per level.
 
 
 
Then, if you have the [[deformed]] or have [[Jiyva mutations#Pseudopods|Pseudopods]], this value is halved rounded down.
 
 
 
All other sources of AC are flat, additive bonuses to your AC score. These are not impacted by Armour skill at all:<ref>{{source ref|0.28.0|player.cc|5914}}</ref>
 
*Value from armour [[enchant]]ment, [[rings of protection]], and [[artefact]] bonuses
 
*[[Ozocubu's Armour]]
 
*[[Protection]] brand
 
*[[Mutation]]s
 
*Innate AC from [[transformation]]s, like [[Dragon Form]] and [[Statue Form]]
 
  
 
==List of Damage that ignores AC==
 
==List of Damage that ignores AC==
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*Prior to [[0.29]], [[Frozen Ramparts]] and [[Ozocubu's Refrigeration]] ignored AC.
 
*Prior to [[0.29]], [[Frozen Ramparts]] and [[Ozocubu's Refrigeration]] ignored AC.
 
*Prior to [[0.26]], [[Irradiate]] ignored AC.
 
*Prior to [[0.26]], [[Irradiate]] ignored AC.
 
==References==
 
<references/>
 
  
 
[[Category:Stats]]
 
[[Category:Stats]]
 
[[Category:Game mechanics]]
 
[[Category:Game mechanics]]
 
[[Category:Defence]]
 
[[Category:Defence]]

Latest revision as of 12:14, 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