### Welcome to the Forum Archive!

Years of conversation fill a ton of digital pages, and we've kept all of it accessible to browse or copy over. Whether you're looking for reveal articles for older champions, or the first time that Rammus rolled into an "OK" thread, or anything in between, you can find it here. When you're finished, check out the boards to join in the latest League of Legends discussions.

### Magic Penetration Question

Uhmm

Senior Member

How exactly does magic penetration work? Which is to say, in what order are % and flat reduction applied?

For example:

enemy has 100 magic resist, i have 20 magic pen and 15% MR reduction. how much resist does the enemy effectively have?

selenvar

Senior Member

65 mpen.

Uhmm

Senior Member

uhh...how does that work?

Larias

Quote:
Uhmm:
How exactly does magic penetration work? Which is to say, in what order are % and flat reduction applied?

For example:

enemy has 100 magic resist, i have 20 magic pen and 15% MR reduction. how much resist does the enemy effectively have?

100 - 20 = 80

80 * .85 = 68

68/168 = 40.47% magic resist

Orange Extract

Senior Member

A recent patch made the percent apply after the flat. Before that it was percent first.

Old way
100 MR * .85 - 20 = 65 MR
New way
(100 MR - 20)* .85 = 68 MR

% reduction goes from
100/(100+100) = 50%
to
68/(100+68) = 40%

A 20% increase in damage.

Larias

Quote:
Uhmm:
uhh...how does that work?

Order goes:

Reduction (abyssal scepter, Amumu's passive etc.)
Flat reduction (Any item that gives a flat +penetration number such as Haunting guise)
% reduction (Masteries/Void staff)

To tell if something is a "reduction" all you have to know is that all reduction effects actually change the visible stat on screen.

0rangeSoda

Recruiter

Magic Pen allows for you to ignore a certain amount of Magic resist
while reducing magic resist does almost the same thing
Magic Pen and Magic Resist Reduction are 2 different things

Uhmm

Senior Member

thank you Larias very informative.

and thanks to you other folks as well

Larias