How does Magic Penetration stack with Magic...

[quote=phexac]For example, you have the offensive Mastery for spells to Penetrate 15% of target's MR. Then you have your 9 MP runes for 8.5 points of MR. And then you have sorcerer's boots for 20 points of MR. So in total you have 15% + 29 flat MR. Now say you have a dude running around with 100 MR. Would your bonuses apply like so: 100-100*0.15-29=85-29=56 ? Just wanted to make sure I got my math right...[/quote]

[quote=Lugignaf]There's a certain order it works in. I think it's Resist reduction first, then flat pen [b]then[/b] %pen. Anyone else wanna back me up on this?[/quote]

[quote=Jebus McAzn]Resist reduction (Abyssal Scepter, etc) Flat penetration (Sorcerer's Shoes, etc) Percent penetration (Void Staff, etc) Percent reduction (Bushwhack)[/quote]

[quote=Searz]What Jebus said. That means that it's: (100-29)*0.85 = ~60[/quote]

[quote=Illuvitarian]I think he's talking about just offensively in which case I believe it's whatever the magic pen % is plus the flat amount of magic pen But if you wanna know what your actually doing to a target with magic res then look at the above statements[/quote]

[quote=TheJohn]But which one is the best? "% pen" or "number pen"? I read the posts, but understood nothing.[/quote]

[quote=Illuvitarian][quote=TheJohn] But which one is the best? "% pen" or "number pen"? I read the posts, but understood nothing. [/quote] It depends on what your opponents magic resist is. If it's 100 obliviously 40% is better then flat 20, (40% resulting in 40 mag pen), but if IRS not high like say 30 magic resist then 40% ends up being like 13 mag pen so a flat 20 mag pen would be better it's really just simple math[/quote]

[quote=caucheka]the best is to get a mix. sorc shoes and the pen runes for champions with low mr. champions with high mr need the mastery and a void staff.[/quote]

[quote=Miraisen]What is the difference between reduction and penetration?[/quote]

[quote=Lugignaf]Reduction is penetration for [b]everyone on your team.[/b] Penetration is just for you.[/quote]