RIOT please look into ZIlean and repatch accordingly.
As Zilean OTP who started leveling new account and play mid instead of support mage role, I can say that Zilean first 10 minutes of the game are probably the worst of any AP mage early game. His low attack damage [52]+ extended animation + short range, combining with low bomb [Q] AP damage and it's extended animation makes him so hard to start the game.
Since ZIlean was reworked (early 2015) he never been patched and since he was reworked LOL roster have changed significantly. RIOT, please either reduce animation time or give some more AD damage for a better early game.
Another thing, Zilean passive have no place in late game.