How does Magic Resist and Armor work?

Comment below rating threshold, click here to show it.

AsherSlasher

Senior Member

02-09-2012

Hey guys I been wondering this for a while, how do the numbers on magic resist and armor work? If i have lets say i have 50 M resist and my attacker has a total of 80 AP, how much damage i will negate? and hows magic penetration affects this?


Comment below rating threshold, click here to show it.

Zero000x000

This user has referred a friend to League of Legends, click for more information

Senior Member

02-09-2012

Learning Center

Damage is modified by 100/(100+resistance). So 50 MR means you take damage*(100/(100+50)) or damage*(2/3). You take 2/3 damage from all magic damage sources (ignoring penetration).
Knowing AP by itself isn't very useful, champions have different base damages and scaling ratios.
Penetration basically means when you are calculating the damage modification based on armor/MR you subtract that much Armor/MR from the target before solving for 100/(100+resistance). Reductions are slightly different, they directly alter your enemy's stats.


Comment below rating threshold, click here to show it.

binch

Senior Member

02-09-2012

Also...

  • Flat penetration reduces the effective Armor/MR of the target.
  • Flat penetration will not reduce a target's Armor/MR below 0.
  • Flat penetration stacks additively.
  • Percent penetration also reduces the effective Armor/MR of the target.
  • Percent penetration is factored after flat penetration.
  • Percent penetration stacks multiplicatively.
  • Penetration applied via debuffs can reduce a targets Armor/MR below 0.


Comment below rating threshold, click here to show it.

gilby

Senior Member

02-09-2012

Quote:
Originally Posted by AsherSlasher View Post
Hey guys I been wondering this for a while, how do the numbers on magic resist and armor work? If i have lets say i have 50 M resist and my attacker has a total of 80 AP, how much damage i will negate? and hows magic penetration affects this?
.


Comment below rating threshold, click here to show it.

Solareclipse460

Senior Member

08-20-2012

Quote:
Originally Posted by Zero000x000 View Post
Learning Center

Damage is modified by 100/(100+resistance). So 50 MR means you take damage*(100/(100+50)) or damage*(2/3). You take 2/3 damage from all magic damage sources (ignoring penetration).
Knowing AP by itself isn't very useful, champions have different base damages and scaling ratios.
Penetration basically means when you are calculating the damage modification based on armor/MR you subtract that much Armor/MR from the target before solving for 100/(100+resistance). Reductions are slightly different, they directly alter your enemy's stats.
From what I an understanding ur right but the formula for 50 MR would be 50/100+50 making it 1/3 damage reduction. If this is what I calculate, could be wrong


Comment below rating threshold, click here to show it.

Soup Miner

This user has referred a friend to League of Legends, click for more information

Member

08-20-2012

Contrary to popular belief, armor and MR do not have diminishing returns. Always keep that in mind.

Edit: Don't get caught up by getting less % damage reduction depending on how much resistance you already have. This is what's really happening:
https://dl.dropbox.com/u/12995203/Images/armorlol.png

You can downvote all you want, but it doesn't make this any less true.


Comment below rating threshold, click here to show it.

fCKzAr

Senior Member

08-20-2012

Quote:
Originally Posted by Solareclipse460 View Post
From what I an understanding ur right but the formula for 50 MR would be 50/100+50 making it 1/3 damage reduction. If this is what I calculate, could be wrong
That's exactly how it works.

There are 4 types of penetrations:

flat reduction - Abyssal. Black Cleaver, Amumu passive...
percent reduction - Xin passive...
flat penetration - runes, Brutalizer, Sorc boots...
percent penetration - Last Whisper, Void Staff...

They apply in this order. Percent penetration stacks multiplicatively, so the 10% mastery and a Last Whisper will give you ~46% penetration.


Comment below rating threshold, click here to show it.

Aruaet

This user has referred a friend to League of Legends, click for more information

Senior Member

08-20-2012

Quote:
Originally Posted by Soup Miner View Post
Contrary to popular belief, armor and MR do not have diminishing returns. Always keep that in mind.
Wut?

first 50 mres

0% mitigation ---> 100/(100+50) = 2/3 damage or 33% Mitigation

second 50 mres (50--> 100)

33% mitigation ----> 100/200 = 50% or 50% mitigation.

The first gives 33% mitigation, the second gives an additional 17%

Another 100 Mres ---> 100/300 = 33% damage or 66%. Even though I added 100 more mres the additional bonus from 100 mres to 200 mres is still only 16 more %.

If that isn't diminishing returns, what is?


Comment below rating threshold, click here to show it.

Fenrir Slakt

This user has referred a friend to League of Legends, click for more information

Senior Member

08-20-2012

It's not about the AP they have, it's all about the base damage and scaling of the ability.


Comment below rating threshold, click here to show it.

Soup Miner

This user has referred a friend to League of Legends, click for more information

Member

08-20-2012

That's why I said not to get caught up with the percentages.
Armor doesn't become less effective. Period. 100 armor will always give 100% more effective health.
However, flat health does become more effective depending on how much resistance you have. There's a point where buying flat health will net you more effective health than buying resistances.

Scenario: You have 300 armor with 2000 health -> you have 8000 EHP (2000 base + 1% more for every point of armor).
1. You can spend 700 gold on 45 armor, which will bring your EHP to 8900 (+900 from more armor)
2. You can spend 1110 gold on a giant's belt, which will bring your EHP to 9720(+1720 from flat HP)