Blitzcrank's R passive
I don't think it should be removed, per se. Just that it should not be a passive on a support character. It's not fun when you get yelled at because you "stole" a kill when your ultimate's passive dealt a tiny bit of damage at just the wrong time. Edit: I'm not talking about when the kill might have gotten away. If your R's passive is up as Blitz and they're within range, then they were also in range for the ultimate you haven't used yet.
The problem is that I didn't WANT the kill. It also steals farm, and when a Relic Shield stack isn't up, that's an issue.