Fizz...

Fizz's E trades damage for mobility, meaning fizz can either go in fully or do some damage and dip out. Also its easily counterable if you just move out of the small radius of it, because once you do that he has lost most of his strength.

Its kinda like the idea of having one ability that is the bread and butter of a kit means that once the ability has been used the champ has the majority of their power removed. In this case for fizz, although his E can be annoying at times it's still fair.