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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]]. 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==
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.

The game tracks AC internally using two decimal places. If AC is not a whole number, this internal number will be rounded in a weighted manner each time damage is taken. For example, with an AC of 10.60, there is a 60% chance of AC being treated as 11 and 40% chance of AC being treated as 10.

<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.

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

===Guaranteed Damage Reduction===
''Main Article: [[GDR]]''

When taking physical damage from a melee, ranged weapon, or throwing 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. Spells and abilities, including 'physical' spells like [[Harpoon Shot]] or [[Stone Arrow]], do not use GDR. Only the player benefits from GDR.

==List of Damage that ignores AC==
*[[Torment]] and [[Holy Word]].
*[[Smite]].
*[[Damnation]].
*'''Shared damage''' from [[Anguish]], [[Injury Mirror]], [[Injury Bond]], [[Uskayaw#Given Abilities|Pain Bond]], or [[spectral weapon]]s (uses the original target's AC instead).
*'''Status effects''': [[poison]], [[sticky flame]], [[flay]].
*'''Hex effects''': [[Pain]] / [[Necrotise]], [[Wand of mindburst|Mindburst]], [[Anguish]], [[Agony]]
*'''Weapon [[brand]] damage''' and '''monster [[attack flavour]]s'''.
** Note that weapon brand damage is often a percentage of AC-reduced damage in the first place.
** 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.
*'''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]].

==History==
*Prior to [[0.32]], AC was not tracked to two decimal places.
*Prior to [[0.29]], [[Frozen Ramparts]] and [[Ozocubu's Refrigeration]] ignored AC.
*Prior to [[0.26]], [[Irradiate]] ignored AC.

[[Category:Stats]]
[[Category:Game mechanics]]
[[Category:Defence]]

Armour class - Revision history

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