A Cassiopeia rework concept

I posted this in the Gameplay thread in response to a Red discussion Cass changes, but I thought I'd also post it here for more visibility. Cass has had a rough time since being reworked, either in power level or loss of identity. One of the things that Cass players always comment on is increasing the importance of poisons both thematically and mechanically.

My personal opinion is that Cass should have an emphasis on poisons and gaining more power upon successfully stacking them. This is what I would suggest Cass's kit be something like (from someone who used to play her quite a bit):

Passive: Toxicology

Whenever a champion within (x) yards is poisoned Cass gains a buff. This buff is modified by the type, duration and amount of different poisons on the enemy.

If an enemy is afflicted by an allied champ's poison or Curse of Vanity, Cass gains vision of the target until the poison wears off or the target dies.

If the enemy is afflicted by Viper Shot, Cass gains movement speed. This speed increases the longer the target is afflicted by Viper Shot.

If the target is afflicted by Viper and Vanity Poison, Twin Fang becomes a targetable ability.

Q: Viper Shot

Blasts the ground with Viper Poison. If afflicted the target takes (x) damage for (x) seconds.

W: Curse of Vanity

When used reflects an ability used on Cassiopeia. If an ability is successfully reflected the target is cursed and afflicted by Vanity Poison which slows them by (x) amount. This slow does not stack but can be extended by successfully hitting the target with Twin Fang.

E: Twin Fang

Fires a skillshot nuke that applies Neurotoxin which inflicts (x) damage and extends the duration of Viper Shot (if already afflicted). ** R: Poseidon's Vengeance**

Applies all three poisons to the target which inflicts (x) damage and chains them to the ground for (x) seconds. For every additional target that Poseidon's Vengeance hits, Curse of Vanity gains an extra charge that is usable without triggering its cooldown.

This kit has a strong emphasis on poisons, interacts with allied champion's poisons and rewards the player for stacking poisons. It would reward skillful play and contains a fair amount of inherent counterplay. What do you think?