The main culprit for me is High Noon Lucian or whatever the skin name is that makes him look like TF.
There's a few others, can't think of them off the top of my head.
Skins are cool and I love them, and I get that's probably Riot's #1 source of income -- but we really need to do a better job of making sure skins don't give any kind of strategic advantage.
If I think Lucian is TF for even .0001 second, that's a disadvantage for me. Even if it doesn't amount to anything -- it shouldn't be happening. It COULD HAVE amounted in something. That's not OK.
We banned some annie skin from pro play a while back because you couldn't see her projectiles.
iBlitzcrank was re-worked at one point because you couldn't see his grab coming.
I think there was something with Zombie Brand at one point, too? Couldn't you tell if a bush was warded or something? I forget.
But anyway -- We need to re-think whether or not is ok for champions to look like other champions just by equipping a certain skin.