Armor penetration

Armor penetration, often abbreviated as AP, refers to the amount of an opponent's AL that will be ignored when calculating damage from a single damage-dealing attack or skill.

To illustrate the basic concept, an attack that has 25% armor penetration against an opponent with 80 AL will give him an effective 60 AL (80 * (1 - 0.25)) against that attack. If the attack would have caused 20 damage against the original 80 AL, armor penetration will increase the damage to 28 (roughly 20 &times; sqrt(2); see the damage article for the explanation). Note that this is a 40% increase in damage &mdash; armor penetration and the damage increase are not linearly related. (This is a common misconception.)

There are two types of armor penetration: base armor penetration and bonus armor penetration:
 * Base armor penetration is a set amount of armor penetration, such as "This attack has 20% armor penetration." If there is more than one source for base armor penetration, the largest value is used; base armor penetration does not stack. Sources include the Strength attribute, Horn Bow-type bows, Penetrating Blow, Penetrating Attack, and many Air-based Elementalist spells.
 * Bonus armor penetration is an additional amount of armor penetration, such as "Armor penetration +20%." These do stack and add to the largest base armor penetration. The only two sources currently available are Sundering weapon upgrades and Judge's Insight. Both only apply to weapon attacks.

Related Skills
These skills cause armor penetration:


 * Core
 * Judge's Insight
 * Enervating Charge
 * Lightning Orb
 * Lightning Strike
 * Lightning Touch
 * Prophecies
 * Penetrating Blow
 * Penetrating Attack
 * Chain Lightning
 * Lightning Javelin
 * Mind Shock
 * Shock
 * Factions
 * Penetrating Chop
 * Primal Rage
 * Sundering Attack