Mpen
Magic Penetration
Cuts through enemy MR.
When you need it
Mages when enemies build MR.
Item examples
Sorcerer's Boots, Liandry's Torment, Void Staff.
Details & formulas
Flat pen applies before % pen.
How to counter it
Stack MR (Force of Nature, Kaenic Rookern). Banshee's Veil blocks the first full ability.
Champions that build it
All mages (Lux, Veigar, Brand) to shred MR. AP assassins (Akali) layer Magic Pen with AP.