Tryndamere
I know there are tons of posts about "Nurf trynd rito pls" but I am thinking about a rework, im not high elo by any means, and there are there are ways to deal with his split pushes. It forces his team to 4v5 but by the time you engage and finish the team fight he has taken the nexus an now has enough gold to shove up your ass. He just ruins so many games, taking from his team and the other. His kit is designed around split pushing, but someone like zed can do the same but will actually die! I just think a little reworking, a little revisiting, and he will be not so annoying. IMO they could make him a much more fun champion.
