For example, an Air Magic spell that grants 25% armor penetration treats a foe with an armor rating of 80 as if it had only 60 armor, i.e.
80 - 25%*80. This would cause approximately ~41% more damage to the target than otherwise, since the increase in damage is dependent on the base armor rating.
There are two different types of armor penetration: base armor penetration and bonus armor penetration.
 Base armor penetration
Base armor penetration is the non-stackable, fixed amount of penetration listed in a skill's description, e.g. "this attack has 20% armor penetration". If there is more than one source, only the highest value is used.
|Strength||1% per rank||When using attack skills|
|Air Magic spells||25%||Each one that deals lightning damage|
| Penetrating Blow
| Penetrating Attack
|Cruel Was Daoshen||10%||Affects only Ritualist skills and only while ashes are held|
|Destructive Was Glaive||20%||Affects only Ritualist skills and only while ashes are held|
|Destructive Was Glaive (PvP)||10%||Affects only Ritualist skills and only while ashes are held|
|Spear of Lightning||25%|
 Bonus armor penetration
Bonus armor penetration is an additional amount of armor penetration, such as "armor penetration +20%". These do stack (adding them together) and add to the largest base armor penetration.
- Sundering weapon upgrades have a 10-20% chance to give attacks an additional 20% AP.
- Hornbows have an additional 10% AP on their attacks.
- Judge's Insight gives an additional 20% to attacks.
- The blessing Warrior's Might grants an additional 10% AP to attacks.