Note: If you are not interested in the calculations, there is a TL;DR at the end.
This is an informative guide about the different mechanics of the stat Armor Penetration, especially for Fury warriors. The main focus of the guide is raiding, but most of it applies to PvP too. I will explain Armor Penetration (ArP), the mechanics behind it, its value compared to Strength (STR) and more. I'm making this guide because there seems to be a lot of confusion about ArP and its mechanics. It’s hard to find reliable information about this on the internet, as most players don’t fully understand how it works. Although I can’t guarantee the mechanics work perfectly here, Trinity Core should have most of this working. If you have any questions, remarks or improvements, feel free to email me at: [email protected]
1) CALCULATING ARMOR PENETRATION
Keep in mind the results from calculations are often rounded, but the exact value is used for calculations after that. I didn’t invent these calculations, it’s just the way the server works.
This is the part that most people have heard. ArP's value compared to other stats increases when you have more ArP. This is a fact. Most warriors also know the ArP cap (1339.6 rating -> 100%), also a fact. Sadly a lot of warriors now draw false conclusions without knowing the mechanics behind it. I will try to explain these mechanics/calculations and draw proper conclusions from those.Quote:
“The more armor penetration you have, the more it’s value increases.”
I'll start off with the calculations involving ArP that the server does. In WotLK 3.3.5 every raid boss has the exact same amount of armor, 10643. Before any of your personal ArP comes into play, the armor can first be lowered with certain abilities, for example Sunder Armor (-20%) and Faerie Fire (-5%). These debuffs stack multiplicatively. This is also where the reduction from Shattering Throw is applied when it's used.
If we have 2 or more armor reducing debuffs, we fill in the formula twice. During most encounters theQuote:
Armor = Armor * (1-reduction from a debuff)
boss will have the 2 main armor reducing buffs on him throughout the entire fight. If we fill in 10643 armor to begin with, and apply a 20% and a 5% debuff, we get 8088.68 armor.
Now a really common misconception is that 100% ArP will remove all of the armor, making the armor reducing debuffs useless. What most people not know is: in most cases not all of the armor is affected by ArP. It is simply because of the calculations behind it. We will call the amount of armor from the boss that will be affected by ArP the ArP cap. It is calculated using the following formula:
The 15232.5 is a constant based on your level. As I assume you're always 80, this constant doesn't change. If we fill in the 8088.68 we obtained earlier, we find an ArP cap of 7773.73 This means you’re your ArP can only reduce 7773.73 armor on the boss. Now with the next formula, we can calculate the armor left on the boss. We will use the term EffectiveArmor for the armor that is used to calculate the physical damage mitigation on the boss from your attacks.Quote:
ArP cap = (Armor + 15232.5)/3
The min{} picks the lower value of the 2, and makes sure that the ArP cap doesn't exceed the armor.Quote:
EffectiveArmor = Armor – ArP rating / 1399.6 * min{Arp cap, Armor}
If we use Shattering Throw, the ArP cap can exceed the armor on the target. Because armor can't go below 0, this can't be the case. The min{} makes sure the EffectiveArmor is always 0 or higher. ArP rating is your personal Armor Penetration rating, the value you see at your character’s info. This is the combined rating of gear, food and procs (like trinkets or Executioner enchant). We divide this by 1399.6 to get the percentage ArP. Then we multiply this by the Arp Cap (or Armor if that’s higher) to get the amount of Armor you reduce. Now we substract this from the Armor on the boss, and we get the armor that’s left.
I didn’t include it in the formula, but all ArP rating above 1400 is wasted. Also many players seem to think there is a sudden dps increase when you reach the cap. It doesn’t work that way. If you need 5 more rating to the cap, an extra gem is not worth it. You would waste 15 rating from the gem, making it far worse than a STR gem.
With the formulas we have so far, we can already draw some conclusions:
1. If you reached the 1400 ArP rating hard cap (and the boss doesn’t have both Shattering Throw and Sunder Armor/Expose Armor on him) there will still be armor left. You will not deal all of your ‘potential’ damage unless you are hard capped and boss has Shattering throw and Sunder Armor/Expose Armor on him. Don’t ever say: “Debuffs are useless once you are hard capped.”
2. On a raid boss, we can only reach 0 armor (true damage) with Shattering Throw, Sunder Armor and 100% armor penetration. (In this case Faerie Fire would be useless)
3. Never ever say that 80% ArP + Sunder Armor means 100% penetration or something
similar to that reasoning.
We now have the EffectiveArmor, used to calculate the reduction on your attacks. The way the server calculates the reduction armor provides is by the following formula:
Damage reduction (DR%) is the percentage reduction on your damaging attacks. If DR% is 0, you deal full damage, if it's 0.5 you only deal half. If the effective armor is 0, the DR% is also 0. The 15232.5 is again a constant based on your level.Quote:
DR% = EffectiveArmor / (EffectiveArmor + 15232.5)
If we want to go from the DR% to Damage Applied (DA%) we use
This one shouldn’t be too hard to follow: if the target’s armor reduces your damage by 0.25, we still have 0.75 left. This means a 5000 damage attack would deal 3750 damage.Quote:
DA% = 1 – DR%
We now can go from Armor Penetration rating, to Damage Applied. Feel free to fill in the calculations and find out how much damage you deal on a boss.
2) CONCLUSIONS FROM CALCULATIONS
With our formulas, we now can calculate the % damage you deal by filling in your ArP rating. With some calculations we can find out a lot. First of all, even if you are ArP hard capped, the two main armor debuffs still provide a 10.95% damage increase. This means applying Sunder Armor is almost always worth it. Second, without any ArP or debuffs, your attacks get reduced by 41.13% (or you only deal 58.87% of your 'potential' damage). Then an important conclusion is that on a raid boss, 1400 ArP increases your damage by exactly 50% compared to having no ArP rating. If a target has one million armor, going from 0 rating to the hard cap still increases your damage by exactly 50%. However, because armor can't go below 0, this isn't true for low armor targets. We can calculate the point where the ArP cap doesn’t exceed the target’s Armor. We set Armor = Arp cap and find 7616.25 armor. Later we will see this point is really interesting. For now, if the target has more armor than 7616.25, 0-100% ArP increases your damage by 50%. If below that armor, it will be less than 50%. Later we will see that even though the 50% increase doesn't change between a 10k armor and a 30k armor target, ArP's value still decreases.
I will show this with some graphs:
Spoiler:Show
Spoiler:Show
Both graphs used the same calculations, except that for the second graph, 3 armor reducing debuffs were applied. We can clearly see that the graphs are increasing faster when you have more ArP, which proves this unique trait of the stat. Although for every ArP rating the second graph gives us a higher damage multiplier than the first graph, the ArP value is actually lower. I will show that with 2 new graphs:
Spoiler:Show
Spoiler:Show
We see that both graphs start at (0,1) because comparing 0 rating to having no ArP gives 1. More interesting is the 1.5 in the left graph at 1400 rating. As I said earlier, 1400 rating gives a 50% damage increase compared to no rating on targets who have more than 7616.25 armor. The right graph is for a boss with the 3 armor debuffs, which brings his armor below that. Because of that, the value of ArP decreases We see 100% ArP only gives around 1.43 times the damage compared to 0 ArP. This means Shattering Throw decreases the value of ArP. However, it still gives a dps increase.
Spoiler:Show
This graph is for PvP or non-boss mobs. It shows the value of Armor penetration on low armor targets. As you can see it increases linearly from (0,1) to (7616.25,1.5). From that point on its value stays the same (50% damage increase for 1400 rating).
Wowwiki has a few tables for this too. Even though their calculations are a bit off, the conclusions we can derive are the same. I'll post the link together with some more good links at the end. Keep in mind Wowwiki shows 1230 ArP rating as the hard cap because it's outdated. "Patch 3.2.2 (2009-09-22): The amount of armor penetration gained per point of this rating has been reduced by 12%." This and together with some more buffs/nerfs/fixes is why you shouldn’t use old sources which were made during for example the Ulduar patch. ArP was simply better at that point in the same gear which gives false conclusions as you probably play on a 3.3.5 server.
Now comes a fact has a dramatic impact on ArP’s value: bleeds are not affected by armor. This changes a lot about ArP on different armor targets. Earlier I said ArP has always the same value if the target has more than 7616.25 armor. Bleeds change this. The damage of your Deep Wounds (DW) and Rend does not depend on your target’s Armor. When the armor of your target increases, the damage of your non bleeds will decrease. The damage of your bleeds however, won’t change. This means the part of your total damage that is affected by armor will decrease on high armor targets. Now a smaller part of your attacks gets increased by ArP, which decreases it’s value. I’m now going to show 2 graphs. One will show that the amount of damage that is affected by ArP decreasing with more armor. The second will show the value of ArP changing on higher armor targets. I’m assuming 17% of our damage is bleed damage on a 10643 armor target while we have a constant 900 ArP.
Spoiler:Show
The graph above shows the non-bleed damage part of your total damage on different amount of armors. Y = 1 means all of your damage is non-bleed damage, which can never be the case cause we always have constant bleed damage. At 10643 armor, Y = 0.83 because of my initial conditions. It may look like the right part of the graph is linear, but it’s not. It approaches 0 slower and slower, as 0 is the asymptote of this graph. A remarkable point is the sudden change of the graph around 7-8k armor. You can probably guess this is the 7616.25 armor point.
We now know the non-bleed part of your damage gets smaller on higher armor. We also know ArP gets less effective on targets below 7616.25 armor. This means there is an optimum amount of armor, where ArP has its highest value. We will see that in the next graph.
Spoiler:Show
This graph clearly shows how the value of ArP changes on different armor levels if we include bleeds. The optimum is 7616.25 armor. If the target’s armor is below this, ArP’s value decreases rapidly due to the ArP cap exceeding the target’s armor. On armor above the optimum, the value of ArP decreases (although slowly) because bleeds becoming a bigger part of your damage. Although you might think ArP becomes more effective on higher armor target, this graph actually shows the opposite. If we fight a million armor target, ArP’s value is really low. In PvP, against popular believe, ArP’s value decreases on high armor targets.
This also means the value of ArP depends heavily on your Rend usage and a little bit on crit chance (more crit = more DW).
3) ARMOR PENETRATION VERSUS OTHER STATS
Now ArP vs Strength (STR). Many people are not sure what they should gem and some point and I hope to give some clarification. Some give certain baselines like “Gem it once you can reach cap”, which can be good in some cases, while it other cases it’s just not the best option. From now on I'm going to assume we always have the two main armor debuffs on the boss at all times.
The major difference between these two stats is: ArP gives a percentage to our damage, while STR gives a set amount. This automatically means there is a breakpoint where ArP surpasses STR. I’ll try to show this with the following example:
Imagine this situation, HIGHLY simplified and unrealistic but good to show the point: We have 1000000 AP. We now can choose between 100 ArP or 100 STR. Obviously the 100 STR will give a really small increase in AP compared to the 1000000 AP we already have. Taking the 100 ArP is by far the best option. Now what if we had only 50 STR. 100 STR would be a really big increase. The 100 ArP would still give us the same percentage, but now this will be lower than the massive increase we got from AP.
Now more realistic:
Imagine we have pretty good gear, giving us 1000 ArP with 20 empty gem sockets. This is a lot of ArP, which is only reachable with tier 10 gear. We now have the option to either fill the 20 gem sockets with ArP (bringing us to the hard cap) or gemming 400 STR. We can calculate that the 400 ArP rating would give us a damage increase of 14.29%. Sadly there are no percentage buffs which increase the amount of ArP rating you have. Now we have to keep in mind that bleeds are not effected by armor. Bleeds include your Rend and Deep Wounds. Deep Wounds is on average 17% of your damage. This simply means ArP is 17% less effective than what we thought. I’ll leave Rend out of this example, but keep in mind if you use Rend, it will make ArP even worse. With this in mind, our damage increase from the 20 ArP gems is reduced to 11.86%.
Now let's see what the other option (gemming STR) would give us. Unlike ArP, STR has a lot of modifiers. The talent [Improved Berserker Stance], Blessing of Kings and the 10% AP buff (for example Trueshot Aura) scale multiplicatively. This means every gem of STR gives us slightly over 58 AP, and our 400 STR gives 1162 AP. Now we have to determine whether 1162 AP is more or less than a 11.86% increase. Unfortunately this is very hard to do without the use of a damage calculator or spreadsheet. A raw estimate is that 1% of AP gives 0.8-1.0% of damage. From these numbers we can calculate we need about 9000 AP for ArP to become better than STR in this situation. If you have below 9000 AP in this situation, gemming ArP will not give more damage than gemming STR. Going from 1000 to 1400 ArP rating will give you a set percentage increase in damage. STR/AP gives a set increase in dps. Of course this is a slight simplification of the real situation, where we have other factors such as rage.
We always assumed we had a constant amount of ArP not changing during the fight. Trinkets with a proc involving ArP change this. Reaching the cap only with a trinket proccing is called the soft cap. In terms of ArP’s value compared to STR, it makes a major difference if you can reach the cap with a trinket proc, or the hard cap. The trinkets have an uptime of 17% average. This means that throughout the majority of the fight, you won’t even be close to the cap. You can calculate the average ArP value you have during a fight but this is often not a reliable representation of the real situation. A good player will synergize his dps cool downs with a ArP trinket proccing, meaning (excluding the extra damage due the proc) you deal a lot more than 17% of your damage during a proc. The best way to find out what to gem is to use a spreadsheet. You can also do your own calculations, but those will be really complex to give an accurate and reliable answer. It is possible for ArP’s value to be so high it’s worth gemming ArP above the soft cap. This means throughout 17% of the fight your additional gems will go to waste. This point requires high tier 9/tier 10 gear and is hard to reach.
4) TL;DR
Here are the main conclusions from the guide:
• 1400 ArP rating is the hard cap.
• Every boss has 10643 armor
• 80% ArP + Sunder Armor is NOT 100% ArP. Sunder always gives an dps increase on bosses
• ArP does NOT apply to all of the armor a boss has, only a part of it
• You can only reach 0 armor with 100% ArP AND Shattering throw AND Sunder Armor/Expose Armor
• Bleeds are NOT affected by armor (and thus not by ArP)
• In general, your ArP gets worse on high armor targets (against common thought)
5) USEFUL LINKS
Wowwiki on ArP:
http://wowwiki.wikia.com/Armor_penetration
Wowwiki on Armor:
http://wowwiki.wikia.com/Armor
The fury warrior guide which covers everything about fury warriors in detail:
http://web.archive.org/web/201302091...ry_compendium/
Make sure to adjust Rawr or Landsoul's to the the bugs on your server if you know them.
Landsoul's Spreadsheet:
http://www.filedropper.com/warriordps2602cexcel07
Rawr 2.3.22:
http://download-codeplex.sec.s-msft....00&Build=21018
