I don't think she's OP. Wanna talk about one-shot potential and teamfight utility? coughVeigarcough I do get that it can be annoying that all she has to do is hit one snare and then sneeze all her spells in your general direction to kill you. But many more champions have similar mechanics, like Blitz, Morgana, etc where if they hit you with their skillshot you're almost garanteed to die.
I would LOVE that they fix her spell's hitbox and visibility though. Her ult will often miss or hit a foe that should/shouldn't have been hit. Also her spells lack visibility, and it gets so much worst on lower settings.
Seriously her three basic spells are just a clusterDuck of flashy lights, even the red circle around her E isn't as sharp as other similar skillshots.