Armor Penetration ValuesFollow

According to EJ Testing, SSC/TK/BT/Hyjal raid bosses have either 7700 armor or 6200 armor before any debuffs are applied. Using the slightly higher number to get a more 'conservative' estimate, then, for the value of armor penetration with the caveat that it will be even more effective when used against lower-armor targets.

7700 Base Armor with a full set of innate armor debuffs (Sunder x 5 - 2600, Faerie Fire - 610, Curse of Recklessness - 800) will give you a base armor value of 3690, or 25.90% mitigation. Incidentally, removing CoReck will pump that mitigation back up to 4490 armor, or 29.84% mitigation... which means that apply CoReck will give you a 5.6% DPS boost if you don't have any additional armor penetration, more if you do or the boss has a lower base armor. It's well worth bringing up with your Warlocks if they're not using it, and especially if they're using CoDoom or CoAgony. Get those slackers to buff the raids DPS (and tank's threat, for that matter), not their own.

Moving on.... at 3690 Armor, what is the value of 100 Armor Penetration? Finding that gives us a good "rule of thumb". We can then determine the value of 100 Armor Penetration at lower values to help determine the effective % boosts, as the more Armor Penetration you stack the larger the impact it receives (which is to say, going from 3000 armor to 2900 armor produces a smaller DPS boost than going from 100 armor to 0 armor).

100 Armor Penetration at 3690 Armor = 3690 / 14247.5 = 25.90% Mitigation vs. 3590 / 14147.5 = 25.38% Mitigation. Inverse the numbers and you get 74.10% DMG vs. 74.62% DMG, or a boost of 0.702% DPS.

100 Armor Penetration at 2790 Armor (3690 - 900) = 2790 / 13347.5 = 20.90% Mitigation vs. 2690 / 13247.5 = 20.31% Mitigation. Inverse the numbers and you get 79.10% DMG vs. 79.69% DMG, or a boost of 0.756% DPS.

100 Armor Penetration at 100 Armor = 100 / 10657.5 = 00.94% Mitigation vs. 0 / 10557.5 = 0% Mitigation. Inverse the numbers and you get 99.06% DMG vs. 100% DMG, or a boost of .949% DPS.

Summary: As a good rule of thumb, 100 Armor Penetration is ~= .75-.8% DPS increase, but especially when you start stacking larger amounts (i.e. Executioner) the value increases significantly until you reach the cap.

Summary: Armor Penetration is a superb stat for PvE. Looking at the new "PvP" cape from Badges, without any additional armor penetration the cloak works out to something like;

34 Stamina
20 Resilience
46 AP
.91% Crit Chance
+.79% DMG to all attacks

It's considerably better than the pretty much any melee DPS cloak this side of Teron Gorefiend even with the high Stamina/Resilience values on it.

For those curious, the Executioner enchant without any additional armor penetration;

840 Armor Penetration at 3690 Armor: 3690 / 14247.5 = 25.90% Mitigation vs. 2850 / 13407.5 = 21.26% Mitigation. Inverse the numbers and you get 74.10% DMG vs. 78.74% DMG, or a boost of 6.261% DPS when it's active.

At least as a preliminary scan, Executioner looks on par with or better than Mongoose for Rogues (it's been shown to have the same PPM as Mongoose/Crusader on the PTR), and a hell of a lot better for Warriors.

Armor Penetration ftw.

excellent job zip. i cant wait for executioner enchant. that with full armor pen gear from S3 looks to make life a lot harder for clothies.

I've been working on that spread sheet.

And reading this post, I added armor penetration to the list and modeled mob armor.

Warrior DPS SS on Curse.