this is my very first guide and not the best at grammar so please be reasonable here/

Zilean from many of the champions Ive seen is the most annoying considering he can do his ulti about every 30 some seconds.

Runes i would probably go straight AP because you dont need anything else if your running out of mana with him feel free to pick up mana runes you dont need colldown runes masteries, boots and your tome should cover you

normally when i play matches i normally only get the first 4 main items listed if you seem to be dying more get a angels which could possibly help
Banshees if your getting attacked first or even a abyssal scepter against heavy magic damage rs

Pros
[*] very annoying
[*] hard to kill
[*] good early game

Cons
[*] only 1 core damage ability
[*] poor end game or mass reviver
[*] counted by health potions

there is many summoner spells you could pick from
teleport- for better map control
clairvoyance- you are still a support
Flash- self explanatory
Ignite- to get that extra damage off
clarity- if you need the mana

you need to level up time bomb ASAP it is what mainly makes you, you as-well as your revive yet you normally don't need to spam your bombs unless they are fully committed to a fight otherwise your just wasting mana which is bad so you could just level up time bomb then time warp then throw the rest of the points in the rewind you wont really use it till later game

I am sorry if this guide was poorly written but i hope it gives you an ideal on how to play him i would love to hear your comment and more

-Thank you