arcanist ziggs 
which all his god dam't ability is in blue color, WHICH IS SAME AS THE FLOOR
spooky gankplank 
which his Barrel's color is shinning green, WHICH IS SAME AS THE HEALTHGOLBE
elementalist lux 
which her skill can choose to be blue, WHICH IS SAME AS THE FLOOR
etcetera
I feel like spiritfire brand's W is more subtle and harder to react to and one of the lux skins, her Q and E are hard to differentiate.
Some are hard to identify. Like the zed and quinn skins that are similar looking. Somebody had a skin of that type and I thought he was a different champ so I died. Also there is a Veigar skin.. he looked like a little soldier or something. He was on my team and I'm trying to guess who tf is this? When we fight he turned out to be a powerfull dude who oneshots and stuns in a massive aoe, so that was nice.
