Zoe's E is extremely loaded for a single ability.
Now first of all I'm not saying she's OP or weak. Just that this particular ability is LOADED.
Through the 9 games I've played her I've come to realize this ability has A LOT for a single spell.
For Starters the skill shot portion of the ability: Variable Hitbox range. Fast Projectile Speed AOE if it doesn't land. (Literal Lollipopping)
Spell Portion: High Base Damage. Good Mana Cost late. Powerful Slow and Stun. Double Damage on follow up from Zoe or her Teammates. Guaranteed 15 - 30% CD refund on champion hit (Unless QSS'd upon Hit)
As for cons of the ability I could really only find 3: Large Hitbox Flat Mana cost (So high b4 u get mana items but better late) Average AP Ratio.
I feel as if Riot wants to target any part of her kit it would be her E. Perhaps removing the CD refund on the Sleep CC, and move it to Q. Which is supposed to be her bread-and-butter. Perhaps on Large, Epic Monster or Champion kills Q gets refunded by 15 - 25%.