Boards›Gameplay

How does Armor/Magic Penetration work?

Rikari··1 votes·621 views

And no,I dont mean "it ignores armor/MR" Like how void staff and lw ignore 35%, how do things like brutaliser and liandrys mathematically affect your defense? like 20+ pen does ig just ignore 20 armor?

5 Comments

EndlessSorcerer5 votes

They are applied in a specific order: -Flat Reduction -Percent Reduction -Percent Penetration -Flat Penetration

So, if you had 100 magic resistance against a mage with Void Staff and Sorceror Shoes, you would effectively have (100-(100*0.35))-15=50MR when damage calculations take place.

Similarly, if you had 100 magic resistance against a mage with Void Staff and Abyssal Scepter, you would effectively have 100-20-(100-20)*0.35=52MR when damage calculations take place.

Only realized when I was typing this up that Flat Reduction applied before Percent Reduction. Always thought that was the other way around.

67chrome2 votes

What this guy said.

Main thing to remember with Reduction vs. Penetration is Reduction is debuff-based, penetration is just an invisible bonus to your stats. That you can see if you click on your champ portrait for the in-depth stats.

So stuff like Abyssal Scepter's aura, Black Cleaver's stacking %shred, or Nasus's Spirit Fire armor/mr shred count as Reduction.

Passive stuff like Darius's Apprehend %armor pen passive, Yasou's %bonus armor post-ult armor pen, Last Whisper, Void Staff, and most runes and masteries are Penetration.

Sailor Mint1 votes

In S2, it used to be FlatReduction > %Reduction > FlatPen > %Pen.

Since they change to flat pen being last, both % based reductions apply multiplicatively at the same time.

TeemoHunter13371 votes

30 magic pen is the same as enemy having 30 less mr.

same with armor pen.

so lets say singed has 100 mr and 100 armor.

lucian has 10 armor pen. so to lucian, singed has 90 armor.

kat has 15 magic pen. to kat, singed has 85 mr.

Sailor Mint1 votes
  1. Flat Reduction (i.e.: Kayle's Passive, Abyssal Scepter)
  2. Percent Reduction (i.e.: Void Ooze and Dragon Strike)
  3. Percent Penetration (i.e.: Last Whisper and Void Staff.
  4. Flat Penetration. (i.e.: Brutalizer, Sorc Shoes.

Technically, since percent pentration and reduction are multiplicative, they are effectively applied at the same time.

Damage Reduction = 1 - (100/100+PostMitigation)

PostMitigation = ((TotalArmor - FlatReduction) * (1-PercentReduction) * (1-PercentPenetration)) -FlatPenetration

If you have 20 MR Shred (Abyssal) 15 Spell Pen and a Void Staff (35%) and they have 100 MR.

PostMitigationMR = (100-20) * (1-0.35)) - 15 80 * 0,65 = 65 52- 15 = 37 Post Mitigation MR

Damage Reduction Before = 1-(100/(100+100)) = 0.5 = 50% After= 1-(100/100+37)) = 0.27 = 27%

More from Gameplay

3 Refunds per season, upvote if you want 3 refunds per season.
Gameplay764 comments
7,167
votes
3 Refunds per season, upvote if you want 3 refunds per season.
Gameplay156 comments
3,510
votes
UPVOTE FOR URF
Gameplay606 comments
2,440
votes
Yes plz.
Gameplay456 comments
1,721
votes
3 Refunds per season, up vote if you want 3 refunds per season.
Gameplay114 comments
1,716
votes
When is ANYONE at riot going to address the awful new player experience?
Gameplay634 comments
1,383
votes

More by Rikari

Braum's passive can't work on you for 8 seconds if he gets 4 stacks
Gameplay79 comments
195
votes
Zed nerf: Shadows expire twice as fast under turrets
Gameplay101 comments
150
votes
WTF RITO
Memes & Games39 comments
119
votes
Gotta feel bad for new players in S6.
Gameplay55 comments
115
votes
The North America server is "Unavailable"
Memes & Games51 comments
101
votes
We should call this meta "The Burst Meta"
Memes & Games80 comments
98
votes