Zoe's W bug when using snowballs
If you use a snowball with Zoe's W and don't hit anything, you get the full cooldown of the summoner spell (40 sec) instead of the normal W cooldown. That is quite annoying and even kills you sometimes, you can't use any other spell during that cooldown even if you try and pick them up.
Of course this only happens in ARAM since the "snowball" summoner spell can only be picked up on howling abyss.