Revisiting Armor Penetration in Wrath

UPDATE: Due to recent Armor Penetration changes, some formulas in this post are no longer correct. For the latest information on Armor Penetration, please visit my new post located here.

Welcome back everyone. I hope all those who had nice, long holiday weekends were safe and enjoyed themselves in whatever they did. Let’s dive right into some math for all you junkies out there!

One of the most popular posts I had on the site, behind the Dummies Guide to Shot Rotations and the list of Shot Rotation Macros, was the Armor Penetration post. And given we are in a new raiding ballgame, I felt it is worth covering again to help determine if Armor Penetration is still such an awesome stat to stack.

Of course Elitist Jerks has been on top of digging up some specific numbers for us, and Lactose, the helpful co-creator of the original Cheeky’s Spreadsheet, informs us that Maexxna has 13083 armor, which is the same in both the 10 man and 25 man versions. Elitist Jerks is reporting that all bosses in 10 and 25 man versions have the same armor value as Maexxna. While they are still collecting data, their initial testing is indicating that this is true. One comment made a great point about all these bosses having the same armor value.

For a casters, nothing is dumber than tossing some random resistance on a boss. It’s “respec or sit”.

Same for melee and armour. Imagine DPS was finally balanced, and then you add another new boss.
If it’s armour is lower than normal, you stack melee. If it’s higher, you stack casters.

So our magic number is 13083. What this also does is give Armor Penetration in PvE a universal value. Regardless of the boss you know it will have the same effect. In BC, on fights such as Teron Gorefiend who had lower armor than other bosses, sometimes it was more beneficial to swap out ArP for other stats. Well given the new Armor Penetration Rating and universal armor values this is no longer the case.

So the first thing we need to figure out is how much damage reduction a raid boss is getting from 13083 armor. When I made the previous thread we had some numbers already laid out for us, including formulas to determine damage reduction. Well the formulas are still technically the same. We just need to fill in some blanks. Previousl the formula for damage reduction calculations was [%Reduction for 70 = (Armor / (Armor + 10557.3)) * 100]. However the number of 10557.3 is no longer correct. But the formula used to derive that number should still be true (We hope). That formula looks like this: %Reduction = (Armor / ([467.5 * Enemy_Level] + Armor – 22167.5)) * 100

Putting this formulate into Excel and replacing Enemy_Level with 80 and Armor with 13083, we see this:

46.20438= (13083/((467.5 * 80) + 13083 – 22167.5)) * 100

So if all these numbers and formulas are still accurate, we see that raid bosses have a 46.2% damage reduction from physical attacks. We can double check this formula again to make sure it is accurate by comparing it to know damage reduction values. As I did in the previous post, let’s use my armor value and adjust the numbers. We leave Enemy_level at 80 (since the Armory calculates my damage reduction off of same level attackers) and replace 13083 with 8489, which is my current armor. That formula now looks like this:

35.7861 = (8489 / ((467.5 * 80) + 8489 – 22167.5)) * 100

And to confirm that, we can use the Armory tooltip to show that I do indeed have a 35.79% damage reduction. So we know that the formula is at least still accurate. Now that we have verified our numbers we can try to determine how effective Armor Penetration is going to be. Let’s simply our formula first for easier number testing before we move on though. We know that the 467.5*80 isn’t changing, so we can make that a static number, which is 37400. The formula is now:

46.20438= (13083/(37400 + 13083 – 22167.5)) * 100

And since we all know our order of operations and that the addition and subtraction order doesn’t matter, we can simply even further by subtracting 37400-22167.5 so the formula looks like this:

46.20438 = (13083/(15232.6 + 13083)) * 100

We know have a formula similar to what we had in BC. Looking back at some old links, this calculator for damage reduction is still accurate as well, by putting in level 80 and 13083 it returns a 46.204% damage reduction. Hooray for correct numbers!

The Armory still isn’t displaying Armor Penetration values yet, so we will have to do some manual addition, but given the numbers we crunched already this will be easy enough. I only have 94 Armor Penetration Rating at the moment, with 35 coming from my Emblem belt and 59 coming from the crafted leggings. We know from the Combat Ratings post that 15.39 Armor Penetration rating is equal to 1% armor reduction (which is a number also supported by the smart folks at Elitist Jerks). So [94/15.39] = 6.1% armor reduction. How much of a DPS increase is that?

If a boss is reducing our physical damage by 46.2% we can obviously assume we are doing 53.8% of our possible DPS. Pretty simple. But we can use that number to figure out our damage increase through Armor Penetration. With my 6.1% armor reduction, we can calculate that it is equal to 798.06 armor ignored, essentially lowering the boss armor value to 12284.937. Let’s recalculate the damage reduction now.

44.64403 = (12284.937 / (15232.6 + 12284.937)) * 100

So with the boss only reducing our damage by 44.64%, we can now figure we are doing 55.35% of our total possible DPS. To figure our DPS gain, we calculate it like this:

55.35/53.8 = 1.0288

So with 94 Armor Penetration Rating, our damage is increased by 2.88%. The two items I chose specifically for their Armor Penetration are providing me with a 2.88% damage increase. So take this into consideration, Piercing Shots, with 3 points increases our armor penetration by 6%. Without any other Armor Penetration we could figure that this talent would only provide us with about the same damage increase since that is just about what my 94 ArP is providing. Which in hindsight seems to be not as strong as similar DPS increasing talents, especially when you can get that from a points in Focused Fired, Improved Tracking, or Ranged Weapon Specialization for example.

But we do have to be fair to Armor Penetration here and remember that we are not the only method of armor ignore on a boss. We can still consider Sunder Armor and other similar buffs/debuffs. A 5-stack of Sunder Armor will reduce a boss’ armor by 3925. Let’s figure out how much damage reduction a boss mob has with only Sunder Armor and then determine how effective that 94 Armor Penetration Rating is. 13083 – 3925 is 9158 so our formula looks like this:

37.547 = (9158/(15232.6 + 9158)) * 100

This means we are doing 62.453% of our total possible DPS before we calculate our personal Armor Penetration. That 6.1% Armor Reduction is now ignoring 558.638 armor, as opposed to the original 798. So while it’s ignoring less armor, what does it do for out DPS? The boss now has 8599.362 Armor. So our formula is now this:

36.08 = (8599.362/(15232.6 + 8599.362)) * 100

Which means we are now doing 63.92% of our total possible DPS. Using the same calculations from above, we can calculate our DPS gain like this:

63.92/62.453 = 1.02348

So by adding in Sunder Armor, our 6.1% Armor Penetration only adds 2.35% damage increase on top of that. Essentially Sunder Armor made our Armor Penetration even less effective, by about half a percent. It’s important to remember that the Warrior is actually reducing the boss armor, so when you fire each shot your armor penetration is calculating it’s value based off the boss’ current armor value, which in this case was 9158. If you were running without a Warrior or they let Sunder Armor fall off the boss, your shots would then calculate based off the original value, or however many Sunders were applied.

So in the end, the real question is going to be what stats do you give up in order to grab that Armor Penetration? The switch to the combat rating system has definitely weakened armor penetration by making it percentage based rather than a flat number. While in Burning Crusade 500 Armor Penetration was always ignoring 500 armor, my 94 ArP rating is not always ignoring the same amount of armor. It definitely shows that Piercing Shots seems to be not worth its points when it is so easy to pick up other talents that increase DPS by flat amounts for fewer points.

I have to admit that sitting down and looking at these numbers has opened my eyes on rethinking the value of armor penetration. The question that is in my head right now is how much haste rating is required to provide a similar DPS increase? We see haste everywhere so has it become a better stat to stack? Or given the choice between armor penetration or haste, which one is more valuable?

So let me mention some non-post related stuff real quick. We are 12 days away from Less QQ, More Pewpew 1 year anniversary! Holy cow! It’s been quite a journey but I will save my musings for that day rather than now. But you can expect another contest with some more in-game give-aways! So keep reading.

Thoughts, comments, mathematical corrections, or need clarification where I might not have been clear, etc etc, leave a comment! And thanks for all your continued reading!

About Drotara

Drotara (or BehemothDan) considers himself a geek on many levels. A web developer and programmer by trade, he has no shortage of geeky hobbies. When not fulfilling husband and daddy duties, he enjoys WoW, the WoW TCG, Magic: The Gathering, and great board games with friends and family.