While you're here, I'd like to make some suggestions:
-
Mana costs: Q and E cost, base damage, effect duration, and scaling appear to be budgeted to account for plant spawns. Put a mana cost on W, and re-allocate the budget for Q to be cheaper with better scaling and for E to have +.25 root duration at every level. Refund the mana cost if the seed is destroyed or expires without germinating.
-
Zyra's base damages are decent, but AP scaling is very poor unless plants can consistently attack. Also, Zyra (especially mid) is extremely item dependent and has a very long ramp-up time. So her scalings are poor and takes a long time to build, but she still falls off pretty hard late game.
I think this is easily addressed by adding to her max seed storage with each rank in ulti or each time she hits 5 points in a basic skill.
- Most Zyras rush Q first in mid, and E in bot. I personally max W first in either lane to be able to spam plants, lane safer, and zone harder. I think this "summoner" Zyra should be recognized through the plant AI improvements. For example, each rank in W causes the plant to prioritize champions for its first X attacks where X is the number of points in W.
This is mostly a mid-late QoL improvement for the current mage Zyra where plants are essentially rendered useless by the presence of a single enemy minion. It also gives support Zyras more interesting choices between safe aoe (Q), better kill setup/peel (E), and stronger zoning and gank safety (W).
This would also give mid Zyra a viable means of laning against assassins who can kill her with virtually zero counterplay 
and super long range mages 
. Maxing W in mid isn't going to get you a lot of kills, but it would at least let you poke enough to better balance matchups that are currently one-sided bloodbaths.
-
Clearly I have tons of (I think) reasonable, choice-based buff ideas for Zyra. I get that they're probably not going to happen. So looking at the passive only, there are a few easy buffs:
A) Increase missile range to mapwide and add AP scaling, % max hp, or scaling based on Zyra's max hp.
B) Completely redesign ulti to the following: Upon death, Zyra unleashes a final empowered ability: Q a flurry of barbs shooting outward from point of death dealing small damage and slowing targets, W plants a dangerous enraged plant and enrages all other active plants, E an aoe root, R an instant knock-up
The point here is that Zyra is slow, squishy, and often focused to remove her cc from teamfights. A versatile cc-based passive should make her a less appealing KOS target and emphasizes her role as an engage/disengage mage and support.
C) Instead of shooting a single thorn, let us continue to attack as a plant for the entire passive duration via AA and using the same damage, scaling, and item effects as a Q plant.
