Cassiopeia Clarity

So I've recently picked up Cassiopeia and I find her to be tons of fun while being the serpent hypercarry that we know and love. However, in a chaotic teamfight, it's a little difficult to know whether an opponent is taking the damage from Twin Fang when the target is poisoned. I think that adding her E to be a critical strike (similar to single-target Karthus Q or Gragas barrel when fully charged) would make it simpler. Again, this is just my personal thought, but it would really help. Does anybody else agree with me, or am I alone? ;-;