Rengar feels so awful to play against.
^title
If he gets even a small lead in the early game he just spams his ult on CD and one shots anyone who tries to leave the base. It's not that he's overpowered or even that strong, he just feels TERRIBLE to play against when he's fed. Literally nothing you can do except hide in your base. Even if you're surrounded by your teammates, he just one shots you and then when you try to lock him down he presses W and not only removes all CC but heals back to full...
It just seems like other champions that can perform similar functions at least have some counterplay or are vulnerable to CC.