Mar 20, - The subject of this article was removed from World of Warcraft in patch From the perspective of a warrior, because armor penetration increases . The formula for the Armor Penetration cap can be simplified to ArPcap. Armor penetration rating will bring you to % during proc. When you reach these "soft-caps" stacking STR will generally be the best choice. Boss X has 10 armour, a prot warrior applies Sunder armour(20%) .. My Resto/Balance Druid: oshelol/simple.