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Armor penetration (sometimes abbreviated ArP or called armor pen) is a number typically appearing on items that indicates the amount of armor ignored by an attack. It is a modifier that directly decreases the value of the armor of your target in combat time. Unlike Sunder Armor and Expose Armor which require active application, ArP items are passive.

Some abilities, enchantments, items, and spells can contribute by adding armor penetration. ArP can be found as both abilities (ex. sunder armor), or as passive statistical upgrades found on equipment pieces (ex. Season 3 PvP armor). Armor penetration reduces the amount of armor that your target has against melee attacks.

ArP is unique in that the more ArP you have, the greater the increase in damage becomes.

Sometimes "armor penetration" is confused with "spell penetration" both of which operate on separate attack tables.

Armor penetration is not a very recent stat. It has seen in Serrated Blades since 1.10. Since itemization introduction of arena set 3, Blizzard has been popularizing the use of this modifier even into .

Contents 1 Armor Penetration Rating 2 Percentage based ArP 3 Armor penetration benefits 4 Countering armor penetration 5 Examples 5.1 Simple explanation 5.2 Normal white hit damage tables 5.2.1 Items and executioner enchant 5.2.2 Rogue damage 5.2.3 Warrior damage 5.2.4 Analysis of the tables 5.3 Diminishing returns of piercing shot and mace specialization 6 Testing the effect of armor ignore 7 Calculating increased damage of armor penetration 8 Skills and talents 9 Itemization 10 Patch changes 11 See also 12 External links

Armor Penetration Rating Edit

Starting in patch 3.0, in preparation for the expansion , all items with Armor Penetration have been modified to a rating system that affects a percentage of armor ignored. This means that gear scales more cleanly with all bosses but has a side effect of becoming less useful on low armor ones.

The conversion rate is about 7 ArP = 1 ArP Rating. So if you had 1000 ArP, you now have 142.8 ArP Rating. In the past, this would have been a 6% gain on a 15k armor foe and a 12.5% gain on an 8k armor foe; at level 80 it now gives a 9.2% gain to both targets.

ArP Rating required to ignore 1% armor
Level 60	Level 70	Level 80
4.69	7.4	15.39

Percentage based ArP Edit

Since some talents operate on percentages such as Mace Specialization and Piercing Shots they operate onto the already existing modifiers. Instead of ignoring armor from the base value of the target immediatley, it takes in account the effects of Sunder Armor, Expose Armor, Faerie Fire and then does a post operation of the value when it calculates mace specialization and piercing shots.

In addition, what this entails for percentage based ArP is that the higher the armor the greater the ArP raw value and the lesser the armor the less ArP raw value. That is to say, percentage based ArP suffers diminishing returns for heavily sundered units in terms of raw ArP value especially for those with very low armor value.

Armor penetration benefits Edit

Armor penetration will increase the normal damage (white) and the and critical damage (yellow) by a percentage significantly for virtually every armored target. But for lightly armored targets it is much greater than having no armor ignore at all.

From a perspective of a warrior, because armor penetration increases damage, a warrior will get a substantial gain in ragerage generation as a result. Also, armor penetration causes the warrior to increase Execute damage.

Opportunistically from a PvP point of view, a warrior or rogue may apply fewer stacks of sunders or expose armor, assuming they have very high armor pen than usual, because they have a head start on armor ignored. Or they may choose to boost the sustained damage further by a percentage significantly by applying more stacks or combo points.

In PvP, players with 500ArP in the beginning of the fight have equivalent of instant 2 sunders throughout the whole fight. Players with 1000 armor ignore have equivalent of 4 sunders throughout the whole fight at level 70. Some PvP sets have equivalent to 1 sunder advantage or head-start.

Countering armor penetrationEdit

To effectively neutralize or counter the effectiveness of armor penetration one could simply increase their armor value in combat time with drinking pots such as [Greater Stoneshield Potion], changing to Bear Form or Moonkin Form, equipping a Shield, or dropping a Stoneskin Totem, casting Inner Fire or Devotion Aura, or speccing in Toughness and Thick Hide, or proccing Ancestral Healing or Inspiration intentionally. You can also enchant your gear with armor for example [Enchant Cloak - Major Armor] to counter armor pen.

Examples Edit

Simple explanation Edit

Some examples: 1k penetration provides a 5.7% increase on an 8k armor target, 6.8% increase on a 5k armor target, 7.9% increase at 3k armor and a 9.5% increase at 1k armor.

This also illustrates how Armour Penetration has increasing returns with itself. Going from 2k ArP to 2.5k ArP nets the same increase as going from 1.5k ArP to 2k ArP, but going from 1.5k to 2k ArP is a higher increase than going from 1k ArP to 1.5k ArP.

Normal white hit damage tables Edit

In these following tables, we assume normal white hit and we are using ArP not ArP Rating. All ArP calculated have to be in the same terms or units so use conversions if you see ArP Rating to return to ArP. In all tables we map the ArP value to the relative percent in damage that corresponds to the exact armor value shown. Empty cells repeat the values to the left since these values emphasize diminishing returns. To interpret the percentages, you could say "I could hit X harder verses Y armor if I did have armor ignore" where X is the relative percent and Y is the armor value of the target on a normal hit.

Items and executioner enchant Edit

Here we analyze the effectiveness of ArP items usually players will use a base ArP value to target. Here we use 500 ArP and 1000 ArP as our arbitrary targets.

Instant normal white damage increase percentage at level 70 due to ArP

Class	Armor type	Armor	500ArP	840ArP	1340ArP	1000ArP	1840ArP	Armor modifier at combat time
Priest	Cloth	2951	3.01	5.19	8.61	6.25	12.33	without Inner Fire
Priest	Cloth	4531	2.4	4.13	6.82	4.97	9.72	with Inner Fire
Warlock	Cloth	2453	3.24	5.6	9.31	6.75	13.36	without Demon Armor
Warlock	Cloth	3311	2.84	4.9	8.14	5.91	11.64	with Demon Armor
Rogue	Leather	4138	2.53	4.36	7.21	5.25	10.28
Druid	Leather	3676	2.7	4.66	7.71	5.61	11.02	in Human form
Druid	Leather	15956	0.76	1.3	2.12	1.56	2.97	in Bear form
Hunter	Mail	6879	1.79	3.06	5.04	3.68	7.14
Paladin	Plate	10746	1.19	2.03	3.32	2.44	4.68	with 2h Mace
Paladin	Plate	16848	0.72	1.22	1.98	1.46	2.78	with 1h Mace and Shield

Instant normal white damage increase percentage at level 80 due to ArP

Class	Armor type	Armor	500ArP	840ArP	1340ArP	1000ArP	1840ArP	Armor modifier at combat time
Priest	Cloth	2020	2.64	4.52	7.44	5.43	10.54
Warlock	Cloth	2072	2.62	4.49	7.38	5.4	10.47
Rogue	Leather	5336	1.84	3.15	5.16	3.78	7.27
Shaman	Mail	15596	0.82	1.38	2.25	1.66	3.14	with 1h Mace and Shield
Hunter	Mail	10013	1.22	2.07	3.38	2.49	4.74
Paladin	Plate	22152	0.55	0.93	1.51	1.12	2.1	with 1h Sword and Shield
Death Knight	Plate	13891	0.92	1.56	2.53	1.86	3.53	with 2h Axe

Number to component correspondence:

*500ArP  = base ArP
*1000ArP = base ArP = Warp-Spring Coil
*840ArP  = Executioner
*1340ArP = Executioner + 500 base ArP.
*1840ArP = Executioner + 1000 base ArP.

Rogue damageEdit

This time we analyze the effectiveness with active skill of Expose Armor which may occur in a very long arena fight:

Instant normal white damage increase percentage at level 70 due to ArP

Class	Armor type	Armor	560ArP	640ArP	1400ArP	2050ArP	2550ArP	2610ArP	2890ArP	3050ArP	3110ArP	3390ArP	3610ArP	3730ArP	3890ArP	3950ArP	4450ArP	Armor modifier at combat time
Priest	Cloth	2951	3.38	3.89	9.04	13.99	18.19	18.72	21.28	21.85	21.85	21.85	21.85	21.85	21.85	21.85	21.85	without Inner Fire
Priest	Cloth	4531	2.7	3.1	7.16	11	14.23	14.64	16.58	17.73	18.17	20.28	22.01	22.98	24.31	24.81	29.27	with Inner Fire
Warlock	Cloth	2453	3.65	4.19	9.78	15.17	18.85	18.85	18.85	18.85	18.85	18.85	18.85	18.85	18.85	18.85	18.85	without Demon Armor
Warlock	Cloth	3311	3.2	3.68	8.54	13.2	17.15	17.64	20.04	21.46	22	23.87	23.87	23.87	23.87	23.87	23.87	with Demon Armor
Rogue	Leather	4138	2.85	3.27	7.57	11.65	15.09	15.52	17.59	18.82	19.29	21.54	23.4	24.44	25.86	26.41	28.16
Druid	Leather	3676	3.04	3.5	8.1	12.48	16.19	16.66	18.9	20.23	20.74	23.19	25.21	25.83	25.83	25.83	25.83	in Human form
Druid	Leather	15956	0.86	0.98	2.22	3.34	4.24	4.27	4.87	5.18	5.29	5.84	6.28	6.52	6.85	6.97	8.03	in Bear form
Hunter	Mail	6879	2.01	2.31	5.28	8.07	10.37	10.66	12.03	12.83	13.14	14.61	15.81	16.48	17.39	17.73	20.75
Paladin	Plate	10746	1.34	1.53	3.48	5.27	6.74	6.92	7.78	8.28	8.47	9.38	10.11	10.52	11.07	11.28	13.08	with 2h Mace
Paladin	Plate	16848	0.81	0.92	2.08	3.12	3.96	4.06	4.54	4.83	4.93	5.44	5.85	6.07	6.38	6.49	7.47	with 1h Mace and Shield

Number to component correspondence for lvl 70:

*560ArP  =              +               +             + Serrated Blades (level 70)
*640ArP  =              +               +             + Serrated Blades (level 80)
*1400ArP =              +               + Executioner + Serrated Blades +
*2050ArP = Expose Armor (5 combo points lvl 70)       +                 +
*2550ArP = Expose Armor +               +             +                 + 500 Base ArP
*2610ArP = Expose Armor +               +             + Serrated Blades (lvl 70)
*2890ArP = Expose Armor +               + Executioner +                 +
*3050ArP = Expose Armor + 1000 Base ArP +             +                 +
*3110ArP = Expose Armor +               +             + Serrated Blades + 500 Base ArP
*3390ArP = Expose Armor +               + Executioner +                 + 500 Base ArP
*3610ArP = Expose Armor + 1000 Base ArP +             + Serrated Blades +
*3730ArP = Expose Armor +               + Executioner + Serrated Blades +
*3890ArP = Expose Armor + 1000 Base ArP + Executioner +                 +
*3950ArP = Expose Armor +               + Executioner + Serrated Blades + 500 Base ArP 
*4450ArP = Expose Armor + 1000 Base ArP + Executioner + Serrated Blades +

Note we are not using imp expose armor.

Instant normal white damage increase percentage at level 80 due to ArP

Class	Armor type	Armor	560ArP	640ArP	1480ArP	3925ArP	4425ArP	4565ArP	4765ArP	4925ArP	5065ArP	5265ArP	5565ArP	5405ArP	5765ArP	5905ArP	6405ArP	Armor modifier at combat time
Priest	Cloth	2020	2.96	3.4	8.29	11.71	11.71	11.71	11.71	11.71	11.71	11.71	11.71	11.71	11.71	11.71	11.71
Warlock	Cloth	2072	2.94	3.38	8.23	11.97	11.97	11.97	11.97	11.97	11.97	11.97	11.97	11.97	11.97	11.97	11.97
Rogue	Leather	5336	2.07	2.38	5.74	17.46	20.3	21.12	22.33	23.31	24.19	25.48	25.94	25.94	25.94	25.94	25.94
Shaman	Mail	15596	0.91	1.05	2.49	7.21	8.28	8.59	9.03	9.39	9.71	10.18	10.88	10.51	11.37	11.71	12.96	with 1h Mace and Shield
Hunter	Mail	10013	1.37	1.57	3.76	11.11	12.82	13.32	14.04	14.62	15.14	15.9	17.06	16.43	17.85	18.42	20.51
Paladin	Plate	22152	0.62	0.71	1.68	4.78	5.47	5.66	5.95	6.18	6.38	6.67	7.12	6.88	7.42	7.64	8.42	with 1h Sword and Shield
Death Knight	Plate	13891	1.03	1.18	2.8	8.15	9.37	9.73	10.23	10.65	11.01	11.55	12.36	11.92	12.91	13.31	14.75	with 2h Axe

Number to component correspondence for lvl 80:

*560ArP  =              +               +             + Serrated Blades (level 70)
*640ArP  =              +               +             + Serrated Blades (level 80)
*1480ArP =              +               + Executioner + Serrated Blades +
*3925ArP = Expose Armor (5 combo points lvl 80)       +                 +
*4425ArP = Expose Armor +               +             +                 + 500 Base ArP
*4565ArP = Expose Armor +               +             + Serrated Blades (lvl 80)
*4765ArP = Expose Armor +               + Executioner +                 +
*4925ArP = Expose Armor + 1000 Base ArP +             +                 +
*5065ArP = Expose Armor +               +             + Serrated Blades + 500 Base ArP
*5265ArP = Expose Armor +               + Executioner +                 + 500 Base ArP
*5565ArP = Expose Armor + 1000 Base ArP +             + Serrated Blades +
*5405ArP = Expose Armor +               + Executioner + Serrated Blades +
*5765ArP = Expose Armor + 1000 Base ArP + Executioner +                 +
*5905ArP = Expose Armor +               + Executioner + Serrated Blades + 500 Base ArP 
*6405ArP = Expose Armor + 1000 Base ArP + Executioner + Serrated Blades +

Note we are not using imp expose armor.

Warrior damageEdit

This time we analyze the effectiveness with active skill of Sunder Armor which may occur in a very long arena fight:

Instant normal white damage increase percentage at level 70 due to ArP

Class	Armor type	Armor	2600ArP	3100ArP	3440ArP	3600ArP	3940ArP	4440ArP	Armor modifier at combat time
Priest	Cloth	2951	18.63	21.85	21.85	21.85	21.85	21.85	without Inner Fire
Priest	Cloth	4531	14.57	18.09	20.66	21.93	24.73	29.18	with Inner Fire
Warlock	Cloth	2453	18.85	18.85	18.85	18.85	18.85	18.85	without Demon Armor
Warlock	Cloth	3311	17.56	21.91	23.87	23.87	23.87	23.87	with Demon Armor
Rogue	Leather	4138	15.44	19.21	21.96	23.31	26.32	28.16
Druid	Leather	3676	16.58	20.66	23.64	25.12	25.83	25.83	in Human form
Druid	Leather	15956	4.33	5.27	5.94	6.26	6.95	8.01	in Bear form
Hunter	Mail	6879	4279	13.09	14.88	15.75	17.67	20.68
Paladin	Plate	10746	6.89	8.44	9.54	10.08	11.24	13.05	with 2h Mace
Paladin	Plate	16848	4.04	4.92	5.53	5.83	6.47	7.45	with 1h Mace and Shield

Number to component correspondence at lvl 70:

*2600ArP = Sunder Armor (5 stacks lvl 80)             +
*3100ArP = Sunder Armor +               +             + 500 Base ArP
*3440ArP = Sunder Armor +               + Executioner +
*3600ArP = Sunder Armor + 1000 Base ArP +             +
*3940ArP = Sunder Armor +               + Executioner + 500 Base ArP
*4440ArP = Sunder Armor + 1000 Base ArP + Executioner +

Instant normal white damage increase percentage at level 80 due to ArP

Class	Armor type	Armor	3925ArP	4425ArP	4765ArP	4925ArP	5265ArP	5765ArP	Armor modifier at combat time
Priest	Cloth	2020	11.71	11.71	11.71	11.71	11.71	11.71
Warlock	Cloth	2072	11.97	11.97	11.97	11.97	11.97	11.97
Rogue	Leather	5336	17.46	20.3	22.33	23.31	25.48	25.94
Shaman	Mail	15596	7.21	8.28	9.03	9.39	10.18	11.37	with 1h Mace and Shield
Hunter	Mail	10013	11.11	12.82	14.04	14.62	15.9	17.85
Paladin	Plate	22152	4.78	5.47	5.95	6.18	6.67	7.42	with 1h Sword and Shield
Death Knight	Plate	13891	8.15	9.37	10.23	10.65	11.55	12.91	with 2h Axe

Number to component correspondence at lvl 80:

*3925ArP = Sunder Armor (5 stacks lvl 80)             +
*4425ArP = Sunder Armor +               +             + 500 Base ArP
*4765ArP = Sunder Armor +               + Executioner +
*4925ArP = Sunder Armor + 1000 Base ArP +             +
*5265ArP = Sunder Armor +               + Executioner + 500 Base ArP
*5765ArP = Sunder Armor + 1000 Base ArP + Executioner +

Analysis of the tablesEdit

• Notice that armor ignore theoretically can exceed the armor of the target. Thus, there is no damage gain in the extra stacks of armor ignore and suffers diminishing returns when ignore armor matches or exceeds the target armor. In addition the more armor ignore one stacks the more rapid the damage increase especially for low armor targets.

• Important thing to note is that the difference in percentage between the priest with and without inner fire is kind of misleading. The percentages are relative to the original armor value at that instant that damage occurred. So comparing percentages outside the original armor value is nonsense.

• To make comparisons to other classes like warrior, you just refer to the armor class (plate, mail, etc) for a general idea.

• The importance to counter armor pen for low armor units is shown in the tables. For druids who do not force themselves into bear form for vs rogues who use expose armor and executioner will take 3 times more damage. But without armor pen changing form gives roughly 34.35% damage increase when comparing human and bear form. For a healadin who doesn't weapon swap will take in increasing damage the more the enemy stacks armor ignore.

• With fully sundered units versus cloth, percentage based armor pen talents of mace spec and piercing shots will ignore 0 armor.

Diminishing returns of piercing shot and mace specializationEdit

Here we will give the amount of ArP expected for fully sundered units.

Diminishing returns for percentage based ArP at level 80

Class	Armor type	Armor (no pen)	Armor (5 sunders)	ArP with 6% ignored without sunder	ArP with 6% ignored with sunder	ArP with 15% ignored without sunder	ArP with 15% ignored with sunder	Armor modifier at combat time
Priest	Cloth	2020	0	121.2	0	303	0
Warlock	Cloth	2072	0	103.6	0	310.8	0
Rogue	Leather	5336	1141	320.16	68.46	800.4	171.15
Hunter	Mail	10013	7088	600.78	425.28	1501.95	1063.2
Death Knight	Plate	13891	9966	833.46	597.96	2083.65	1494.9	with 2h Axe
Shaman	Mail	15596	11671	935.76	700.26	2339.4	1750.65	with 1h Mace and Shield
Paladin	Plate	22152	18227	1329.12	911.35	3322.8	2734.05	with 1h Sword and Shield

When analyzing armor classes, if you look at the ΔArP for both 6% and 15%, you see it converges toward 0 from high armored units to very lightly armored units when fully sundered. Also, when analyzing with and without 5 sunders, you see that the ArP value drop.

Testing the effect of armor ignoreEdit

A simple test that people do to check armor ignore effects is to buy pieces of armor in the auction house and add and remove pieces of armor. Usually one will inspect the character sheet tooltip when they highlight over armor. The armor reduction at level X will change by a percentage or a fraction of a percentage.

Calculating increased damage of armor penetrationEdit

Ar = Number that appears in tooltip

Ar1 = Armor reduction (with penetration)
Ar2 = Armor reduction (without penetration)
F = Full damage = 100%

Damage under effect of Armor = Full damage - Damage Reduced by Armor

De = F - Ar

De1 = Damage under effect of Armor (with penetration)
De2 = Damage under effect of Armor (without penetration)

R = reference damage that can be any arbitrary number

De1 = R*(100% - Ar1) #damage effect with penetration
De2 = R*(100% - Ar2) #damage effect without penetration

ΔDe = De1 - De2

I = ΔDe/R

I = (De1 - De2)/R

I = ((R*(F - Ar1) - R*(F - Ar2))/R

I = (F - Ar1) - (F - Ar2)

I = F - Ar1 - F + Ar2

Damage increase I is:

• I = Ar2 - Ar1

Skills and talents Edit

• For rogues they have Mace Specialization, Serrated Blades. Some players consider Expose Armor as armor pen.
• For warriors they have Mace Specialization. Some players consider Sunder Armor as armor pen.
• For hunters they have Piercing Shots.
• For druids they have Faerie Fire.
• Expose armor and sunder armor effects do not stack. Both have a chance to not apply (miss) when one uses these skills.

Itemization Edit

Warrior sets:

• Onslaught Battlegear
• Vengeful Gladiator's Battlegear
• Brutal Gladiator's Battlegear

Rogue sets:

• Vengeful Gladiator's Vestments
• Brutal Gladiator's Vestments

Hunter sets:

• Gronnstalker's Armor
• Vengeful Gladiator's Pursuit
• Brutal Gladiator's Pursuit

Weapons:

• [Thori'dal, the Stars' Fury]

Trinkets:

• [Icon of Unyielding Courage]
• [Badge of the Swarmguard]
• [Warp-Spring Coil]

Enchants:

• [Enchant Weapon - Executioner] note: 2x Executioner do not stack.

Gems:

• [Fractured Cardinal Ruby]
• [Puissant Dreadstone]
• [Fractured Dragon's Eye]

Patch changes Edit

• As of Patch 2.4.1, Armor Penetration will now display on the character sheet (Armor Penetration displays in the hit rating section).

See also Edit

• Damage reduction

External links Edit