For Neggles, Maevet, and anyone who will listen.

Sup. So specifically, this is a post aimed at Neggles and Maevet, but anyone's welcome to read. Specifically, it has to do with my recent trash-talking of Armor Penetration and why it's such a sub-par stat to gear for in Wrath.

We all know how Armor Penetration works now, right? You have X armor penetration, and it shaves that much armor off your current target. The more you get, the better it works, because armor is a scalar statistic - the more of it you have, the weaker gaining X more is. Conversely, the more ArPen you have, the STRONGER gaining X of it is, until your target has 0 armor.

Bosses have, usually, between 6200 and 7700 armor. I'm still trying to find an exact table of who has how much, and if anyone has one, I'd <3 you forever. But, aside from that, you have to remember that in Wrath, there's two kinds of armor reducers: Major and Minor. Sunder Armor is the most common Major Armor Reduce debuff that you'll encounter - five stacks of this is 2600 armor. Faerie Fire is the most common Minor Armor Reduce debuff of those that exist - that's another 610. Adding that up, your raid members are shaving off 3210 armor for you.

Now, before, your Armor Penetration continued to work against the armor that was left after the 3210 removed by your raid members. And this was great! The more you had, the closer you got to the Zero-Armor point, at which you're doing full damage. Sadly, however, Armor Penetration Rating changes all that.

At level 70, 7.5-ish ArPen Rating is 1% armor penetrated. Take a 6200 armor boss, like one from BT. 6200 - 3210 = 2990. Now, take a decent ArPen item... Oh, how does Steadying Bracers sound? In TBC, you're getting 105 ArPen out of them, putting you at 2885 Armor to fight against once you slip them on. However, in Wrath, they get changed to look like this. 15 Armor Penetration Rating. Now, given that it's roughly 7.5:1%, that means you'll punch through 2% of that 2990 figure. But wait! That's only 59.8 armor - only 56% as strong as it used to be! It gets worse, too. :(

Building out a armor penetration set of stuff that I see on WoWHead, I can get to 868 Armor Penetration rather easily. I'm not even really trying here. But if I turn that into ArPen Rating, that becomes 125 Rating. That's 16.6~% of the armor after debuffs that's shaved off - 498.3~ armor, in other words. Now it's down to 57% of what it used to be - the more ArPen Rating you get, the WORSE it is against an equal amount of ArPen.

And given how high things scale at 80... Ick.

Just say no to ArPen Rating (and Haste, too). :P