Also, armor penetration causes the warrior to increase Execute damage.
Black Ops 4.
A level 80 warrior creature has armor.
The problem was, Armor Pen was such an unambigulously better stat there was no choice.
Computing the cap is a little tricky unless you are already familiar with how World of Warcraft armor works.
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In short, armor penetration is really only countered by more armor.
What other items should I look for?