[{quoted}](name=Ash Lockheart,realm=NA,application-id=3ErqAdtq,discussion-id=EIHuOrhG,comment-id=0000000000010000,timestamp=2015-06-28T08:34:30.514+0000)
15% is not much. Vi's can do 20%. Besides Karthus Mana burns the fastest. I still don't see much Karthus brings to the game Even if you play well and get fed. I still see him being very weak for his kit.
Armour isn't MR though. Are there any other champ abilities that take away more MR save Trundle's ult?
He brings more damage than literally every other mid laner in the game. His team fight presence is huge, and focusing him is a heavily risky prospect because of his passive, which allows him to do even more damage.
His weakness is one of the weakest laning phases in the game.