Zyra passive suggestion
I know Zyra is going to get an update eventually, along with many other mages. I think that her kit is pretty good in it's current state, but she needs a new passive.
New passive: "Massive roots"
Zyra shares a large root system with her plants. Whenever one of Zyra's plants pop up, Zyra will absorb nutrients and restore a small amount of health and mana. The amount scales with level.