User blog comment:HozzieHozzbourne/Strongest champion outside of the game/@comment-8506165-20130920052507

Kassadin's an interesting one because all the mages mentioned here are weak against his magic, but much like in-game, there's no hint at him having any particular power beyond mage-killing (and hell, he hadn't even won his duel against Malzahar when the League interrupted it).

Fids deserves some recognition. He kills(or drives insane) anyone that goes into his room at the Institute of War. Anyone. That includes summoners who are meant to be some of the most powerful mages of the day.

Swain should get more credit than he's given. He's hinted to not be entirely human, constantly goes around with his raven on his shoulder and transforms into a giant demon bird. But if it's just "who wins in a straight-up fight" I'm not sure he'd be up there. Hm.

Anivia's an immortal embodiment of ice magic. Probably at least warrants an "honorable mention".

Tried to go beyond the "obvious mentions" here... Syndra, Xerath, Annie when she grows up, etc.