How about a champion with a lot of mobility who depends on making several passes in order to kill someone. IE someone who comes in, does their damage putting you around 60% HP and then got out, and then they come back putting you at 20% HP and then got out, and then come back and kill you, and then got out.
Maybe not exact numbers but you know how about an assassin that gives you a chance to make strategic decisions instead of one who just appears, kills you before you can respond and is instantly gone spamming /laugh.
Having crazy mobility should cost you damage as it should be a requirement that you USE that mobility to get into and out of fights over the course of a long fight to kill your target, not that you get to instantly delete people while coming and going as you please.