Who are the most hidden-OP champs?

Not ones bitched about on boards. Ones that are rarely played but still incredibly annoying / overpowered. I have a few: I hate this kid, and it's pretty surprising how much he has in his kit if you analyze it. Free sustain, CC ALL THE TIME, hypermobility that you can NEVER see coming, and to top it all off, a revive in case you screw up. IMO this kid needs to be nerfed; I don't even see the point of his healing...

JESUS I hate this champ. I'm not really sure why, but I just hate her. She's rewarded way too easily. If you land her super-large Q you get a free ~900-1000 damage late game with your E. Your ult is annoying as hell. And the wall that every Anivia on YOUR team misses, but every anivia on the other team goes Faker. She can get 2-3 revives depending on the team comp, also.

What the fuck. Who thought giving a champion 3-second teleports was a good idea? "Oh but the mana cost doubles!!!" Who cares? You probably have 1000-1500 mana anyway, enough for 3-4 teleports, and it resets every 15 seconds so when you're out of a teamfight it's basically free. Everything about this champion is free. Targeted Q with silence. Free teleports. He does so much damage too. You can't even get near this guy without popping instantly.