In a most recent game i was playing against a Cassiopeia. During the lanning phase ive noticed that her W animation couldn't been visually seen. i also asked an ally to confirm this and he also had the same situation. 
I was playing against a skinned Cassiopeia (Desperada) and I could only see the animation of her throwing her W, but I was never able to see the affected area. When I walked through the affected area I was slowed and poisoned, but I couldn't see the ability on the ground.
It's been like a hundred of this bug report, it's just that riot does not give a shit about cassio. They can't even fix her bugs.
