After killing an enemy ward, a friendly Zombie Ward is raised in its place.
Arcane Comet is a reasonably good rune for Zoe in the laning phase thanks to her ability to poke repeatedly with [Q].
While you don't have many tools to help you land the Comet, hitting the enemy with [E] before setting up with a long range [Q], the Comet is guaranteed to hit and the damage can be the difference between a kill and their survival.
WhyThe Ultimate Hat
Zoe's super low cooldown on [R] allows her to almost instantly get the full stack benefit of Ultimate Hat keeping it at an even shorter cooldown.
More [R] blinks means more opportunities for massive long range [Q] bursts.
If you're playing into a high damage AP mid (Syndra/LeBlanc), Nullifying Orb can be a valuable alternative to avoid early deaths.
Transcendence allows you to hit 40% CDR with just Morello's and Lich Bane, making your mid game damage and utility threat incredibly powerful.
Scorch further empowers your ability to chip away at the enemies health bar during the lane phase. The extra bit of damage helps you come out ahead in trades and find early kills.
Zoe is able to reliably proc Sudden Impact with every cast of her R], being able to keep the Magic Penetration buff up at all times in the mid to late game for even more burst damage.
Zombie Ward offers incredible lane safety vision around the sides of mid to keep you safe from ganks and able to track the enemy jungler more often.