Randomizer
Amazingly enough, when studying for my exams, I started to think of League of Legends (wooooow), and I came to think game modes. Wouldn't it be fun to have a game mode where the champions abilities were scrambled? Abilities would of course be appropriate to their auto attack ranges and damage types, so that no champ would suffer from having to build something their champ would not naturally benefit from or having a useless ability late, and it would be stupid if range champed started doing all sorts of melee stuff when their priority is ranged (imagine caitlyn jumping around like riven XD). Abilities like dashes, CC etc. would be a different matter, of course. It's just a quick thought, though, you're welcome to refine this idea.