Armor penetration

Summary

• 1 Order of calculation
• 2 Fixed armature reduction
• 3 Armor reduction in percentage
• 4 Armor penetration in percent
• 5 Fixed armor penetration
• 6 Examples
• 7 Increasing armor penetration
  • 7.1 Objects
  • 7.2 Champion skills
  • 7.3 Masteries
  • 7.4 Speech
• 8 Reducing armor
  • 8.1 Objects
  • 8.2 Champion skills
  • 8.3 Summoner spells
• 9 Notes
• 10 References

La armor penetration is a champion stat that allows the champion to ignore some or all of their target's armor. All champions have 0 base armor penetration, but can increase it with items, runes, masteries, and some champion abilities. Armor Penetration cannot reduce enemy armor below 0 to deal bonus damage.

La armor reduction is the effect of one or more champion items and abilities temporarily reducing the armor of one or more targets. Armor reduction can reduce enemy armor below 0, thus dealing additional physical damage (see Armor).

Calculation order

When attacking, armor penetration and armor reduction are considered in the following order [1]:

1. Armature reduction, fixed
2. Armor reduction, in percent
3. Armor penetration, in percent
4. Armor penetration, fixed

Fixed armor reduction

The target's armor is reduced by a fixed amount. Fixed armor reduction stacks additively.

Example: 20 armor reduction reduces the target's armor by 20, so a target with 30 armor will have 10 armor (30 - 20 = 10).

Fixed armor reduction can reduce the target's armor below 0. For example, if an enemy with 10 armor has their armor reduced by 25, they will be left with −15 armor.

Armor reduction in percentage

The target's armor is multiplied by a percentage (100% - the marked reduction). Armor reduction in percentage stacks multiplicatively and is ignored if the target's armor is less than or equal to 0.

Example: 20% armor reduction multiplies the target's armor by 80%, so a target with 30 armor will see it reduced to 24 armor (30 × 0.8 = 24).

The percentage armor reduction makes a bigger difference on heavily armored targets. For example, with 40% armor reduction, a target with 200 armor would lose 80, while one with 50 armor would lose 20.

Armor penetration in percent

The target's armor is treated as if it were multiplied by a percentage for damage calculation purposes (100% - the marked penetration). Armor penetration in percent stacks multiplicatively and is ignored if the target's armor is less than or equal to 0.

Example: 20% armor penetration causes the target to take damage as if their armor was multiplied by 80%. A target with 30 armor will be treated as having 24 armor for damage calculation purposes (the actual armor value of the target does not change, however).

Since the target's armor value does not change, anything that depends on that value will not be affected (for example, Defensive Position of Rammus).

Armor penetration in percentage makes a greater difference on heavily armored targets. For example, at 40% armor penetration, a target with 200 armor would lose 80, while one with 50 armor would lose 20.

Fixed armor penetration

The target's armor is treated as if it were reduced by a specified amount for damage calculation purposes. Fixed armor penetration cannot reduce enemy armor below 0; it accumulates additively.

Example: 20 armor penetration causes the target to take damage as if they had 20 less armor. Thus, a target with 30 armor will be treated as having 10 armor for damage calculation purposes (the actual armor value of the target does not change, however).

Since the target's armor value does not change, anything that depends on that value will not be affected (for example, Defensive Position of Rammus).

Examples

If you have 20 fixed armor reduction and 30% armor reduction, and the target is affected by 10 fixed armor penetration and 35% armor penetration,

• Target A has 80 armor.
  • The 80 is reduced to 60 due to the 20 armor reduction.
  • The 60 is reduced to 42 due to the 30% armor reduction.
  • The 42 are considered as 27.3 due to 35% armor penetration.
  • The 27.3 is considered 17.3 due to the 10 armor penetration.

Target A takes damage as if it had 17.3 armor.

• Target B has 18 armor.
  • The 18 are reduced to −2 due to the 20 armor reduction.
  • The −2s are not affected by other calculations since it is less than 0.
    • Target B takes damage as if it had −2 armor.

Increasing armor penetration

Objects

• Last Whisper: Unique Passive: + 35% Armor Penetration. +40 Attack Damage. 2300 gold.
• Youmuu Ghost Sword: Unique Passive: +20 Armor Penetration. +30 Attack Damage, + 15% Critical Strike Chance, + 10% Cooldown Reduction. Unique Active: Grants + 40% attack speed and + 20% movement speed for 6 seconds (45 second cooldown). 2700 gold.
• The Dark Blade: Unique Passive: +10 Armor Penetration. +200 Health, +50 Attack Damage, + 10% Cooldown Reduction. Passive: Dealing physical damage to an enemy champion reduces their armor by 5% for 4 seconds (stacks a maximum of 5 times, up to a maximum of 25%). 3000 gold.
• Warrior

Champion abilities

Please note: Only the armor penetration effect of these skills is shown, to read more information about each one, follow the corresponding link.

• Apprehend from Darius passively grants him 5/10/15/20/25% armor penetration.
• Last breath of Yasuo, when activated, grants him an additional 50% armor penetration.

Master Degrees

• Devastating Strikes Devastating Strikes grants 2/4/6% armor penetration.

Runes

• Armor Penetration runes provide fixed armor penetration.
• Hybrid Penetration runes provide fixed armor and magic penetration.

Reducing armor

Objects

• The Dark Blade: Passive: Dealing physical damage to an enemy champion reduces their armor by 5% for 4 seconds (stacks a maximum of 5 times, up to a maximum of 25%). +200 Health, +50 Attack Damage, + 10% Cooldown Reduction. Unique: +10 Armor Penetration. 3000 gold.

Champion abilities

Please note: Only the armor reduction effect of these abilities is shown, to read more information about each one, follow the corresponding link.

Percentage reduction:

• Dragon Strike Jarvan IV reduces the armor of all enemies hit by 12/16/20/24/28% for 3 seconds.
• Transform: Mercury Cannon Transform: Mercury Cannon from Jayce reduces the armor and magic resistance of the enemy hit by his first attack after using the ability, by 10/15/20/25% for 5 seconds
• Sacred Fervor Sacred Fervor of Kayle reduces the armor of enemies hit by her basic attacks by 3% for 5 seconds. This buff stacks up to 5 times.
• Caustic drool of Kog'Maw reduces enemy armor and magic resistance by 12/16/20/24/28% for 4 seconds.
• Cut and Chop of Renekton, when gaining power over 50 Fury, Shatter reduces the armor of all enemies hit by 15/20/25/30/35% for 4 seconds.
• Assassin's Roar Sion reduces the armor of the first target hit by 20% for 2.5 seconds.
• Subjugate Trundle reduces his target's armor by 20% and gains the same amount. This amount doubles over the next 4 seconds. The armor reduction lasts for another 4 seconds after the drain completes.
• Noxian Corrosive Load Noxian Corrosive Load Urgot reduces the armor of all enemies hit by 12/14/16/18/20% for 5 seconds.
• Denting Blows Vi reduces the target's armor by 20% for 4 seconds after every third consecutive hit.
• Crushing Blow of Wukong reduces the armor of the target hit by 10/15/20/25/30% for 3 seconds.
• Challenge of Xin Zhao reduces the armor of targets hit by his basic attacks or by Charge Audacious by 15% for 3 seconds. Only one target can be Challenged at a time.

Fixed reduction:

• Cannon repeating Corki fires automatically every half second, reducing enemies' armor with each hit by 1/2/3/4/5 for 2 seconds up to 8 maximum stacks, 8/16/24/32/40.
• Spiritual Fire of Nasus reduces the armor of all enemies within the area by 20/25/30/35/40 for as long as they are in it plus 1 second.
• Stinging Provocation Stinging Provocation of Rammus reduces the target's armor by 10/15/20/25/30 for 1.25 / 1.5 / 1.75 / 2 / 2.25 seconds.
• Fragmentation of Taric reduces the armor of all enemies hit by its activation damage by 5/10/15/20/25 (+ 5% armor) for 4 seconds.

Summoner spells

• Exhaustion reduces the target's armor and magic resist by 10.

Notes

• Armor Penetration is a very valuable stat for champions who deal physical damage. There are few sources of penetration, which is why armor penetration runes are popular.
• Armor Penetration benefits all sources of physical damage, including all champion abilities that deal physical damage.
  • For example, Increasing Sweep Increasing Sweep of Xin Zhao benefits from armor penetration as it deals physical damage. However, their Fearless Charge will not benefit as it deals magic damage.
  • Objects that deal physical damage on impact: Tiamat, voracious hydra, Brightness, Iceborn Gauntlet and  Trinity Force, also benefit from armor penetration.

References

1. ↑ If I technically had 100% armor reduction on an enemy... en League of Legends (inglés).

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