OLAF
when a lv 2 Olaf can solo carry a 6 vs 1 against 2 lv 3s and 4 lvs 4's, even when they have red buff and morellos... you know the unit needs a nerf...
I have both abused it and played vs it and think it is sickening. you rush a BT and then itemize any combination of Dragon claw, thornmail, giant slayer, rageblade,sword breaker or hush and he's damn near unkillable...
I know i cant be the only one to think the unit is broken and nearly impossible to balance. yes he is item dependent, but once you get a BT, you can use him in any comp.