Armour class

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 artefacts, 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 to offset its penalties.

Armour can be enchanted with scrolls of enchant armour to grant bonus AC.

AC damage reduction

In general 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 always precisely true: against melee attacks, body armour can provide guaranteed damage reduction based its base AC, and some attacks (such as constriction) can partially bypass AC. See the AC calculations page for more details.

List of attacks or sources of damage which are not reduced by AC

• Special damage caused by weapon brands, attack flavours (except pure fire which is is used by fire elementals and fire vortexes) and magical staves (except the staff of earth and 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.
• The following monster spells, abilities, or scrolls: Torment, Holy Word, Smite, Hellfire and the chilling blast breath attack of a white draconian.