Full-damage shaco can be pretty brutal in teamfights in soloq, when you don't have the coordination to all focus him the moment he shows up. He's something like a rengar, but doesn't need to wait for ult to come up to do the whole jumping stealthing on top of your carries-thing. Full-damage shaco can appear on top of a carry in the middle of a teamfight, instantly kill them, then box/ult/deceive away to safety before people focus him down.
That shaco splitpush sure makes you pull your hair out too.