Talk:VPBE/@comment-27080952-20151212022333/@comment-7633726-20151212041512

Flat armor penetration applies to all armor (base and bonus), whereas bonus armor penetration means it only applies to bonus armor. The difference is the armor every champion starts out with is base armor, the armor you get from runes, masteries, abilities, and items are all bonus armor (excpt where stated othrwise). So, for example, you get 5 armor pen from one of the masteries in the Ferocity tree. That armor pen will apply to all armor. But if you buy Lord Dominik's Regards, for example, the 40% (on live, 45% on th PBE) armor pen will only apply to bonus armor. The main difference between the two is flat armor pen in better against squishies who don't build much if any armor (so ADC's and such), where the bonus armor pen is better against tanks. Flat armor pen is better early in the game, th bonus armor pen won't become truly relevent until a bit later, but both are good options and both are viable. I hope this helped.