User blog comment:Deshiba/Season 3 Armor and Armor Penetration/@comment-5523473-20121110025051

I might be wrong here man, but I think your calculations might be in the wrong order. I think it's now %reduc > flat reduc > %pen > flat pen. also, flat and % pen doesn't take a target's armor below zero so Renek wouldn't hit for more than true damage :P (although i'd totally love that to happen xD)