Hello guys,
This is my first guide ever made ! I'm French, then my english isn't perfect, but i'll try to give you the best of me ! I would like to say that this build isn't finish and it's not the ULTIMATE guide of the earth to beat everyone everytime (but maybe .. one day .. it will be :D) ! I'm working on it again and again.. I'll complete it as soon as possible !

Zilean is THE champion : powerful and useful ! Your mates will love you with your ultimate and you'll love your Q spell when you'll hit 2+ people !

I'm an old Silver (Season 4 and 5), but this season I was put in Bronze 2 (thanks Riot --') and I started to play Zilean for the first time in Ranked games.. and that was the better choice I made this year ! Three month later I'm Diamond V with over 350 games with Zilean-sama !

The goal of this build is to reach 45% cooldown reduce ASAP ! More bombs you put on the ground, more you are efficient and your ultimate is happy to be spam ;)
Guardian angel is my little personal way, I didn't see people play with this item.
This build is for a Zilean support, but you can also use it on mid lane (maybe prefer the second item set).

Spells !
Time in a Bottle : During the game you will earn experience for you and one of your mates, use it correctly !

• TIPS : Try to level them ASAP, because in earlier you use your passive for the level up more experience you and your mate will earn.
• Level 3 : Is a powerful level in LoL, you got almost every spell, your combo (QEWQE or QWQE or EQWQE) is ready! Take advantage of it, reach it before ennemies and trade them.
• Level 6 : Now you and your ADC are better than never ! Your ultimate make you feel like a God, you have the choice of live or die.
• Level 11 : Ultimate level 2 is more powerful than level 1 ;)
• Level 11+ : After the level 11 you can level up everyone when you want.

Time Bomb : You can target champion for be sure to make damage and put the stun on the second bomb, but it's possible to do that with a sneaky move, indeed if you put your double bomb on a creep about to die near the ennemies, your double bomb will explose in the same time with (of course) the stun effect and the enemies will be suprised to suffer this damages, if your ADC follow your move it's often a kill for your team.

Rewind : The key of the power of Zilean, spam your spell again and again it's a pleasure ! Trust me.

Time Warp : Slow or speed people up to 99% is really funny ! Try to speed up your ADC to catch a kill if you are behind or slow the target near you, find the better way to play, it's very situational.

Chronoshift : Your mates will love you and you ennemies will hate you a lot ! Revive the carry or your bigger tank will change the fight for your team. Do it !

Combo !
I think Zilean have the largest number of combo in LoL, thanks to his Rewind (W). Let's talk about it :

Time Bomb + Rewind + Time Bomb (Q+W+Q) : It's the stun's way ! put it on champion and you'll deal a lot for you team, or on creeps for a simply clear wave.

Time Warp(on you) + Time Bomb + Rewind + Time Bomb + Time Warp(on ennemies)(E+Q+W+Q+E) : Perfect combo to catch people without escape, they are yours.

Chronoshift(on you) + Flash + Time Warp(on you or ennemies) + Rewind + Time Warp(on you)(R+F/D+E+W+E) : Run for your life kid ;)

Of course this isn't all of combo with Zilean, you can also combine "Run for your life kid" and "the stun's way" x) everything is possible with Zilean.

Frost Queen's Claim : A powerful item for support or MID lanner, you can slow people and search them where they are out of the battlefield once every 90sec.

Eye of the Watchers : Must have if your team have some visions problems.

Morellonomicon : AP + mana + cooldown reduce ? Tell me, what do you need more on Zilean ? [Must Have]

Liandry's Torment : AP + magic penetration + damage over time ! With Morellonomicon no one will regen against you.

Ionian Boots of Lucidity : Ideal item for reach the 45% cooldown reduce.

Guardian Angel : My little pleasure ! Kill someone once is possible, twice may be harder BUT THREE TIMES with your ultimate is very very very difficult ;) And if you have your personal revive item, your ultimate will be always for your mates, they will thank you for that.

Rabadon's Deathcap : Free AP, why not ? Your bombs will deal more damage.

Vision Ward : Remember to buy it [Buy a pink save a life ;)]

Sightstone : This isn't necessary if your team understand how to ward correctly.

Ferocity

Sorcery : Obtain AP, is better than AS on Zil.

Expose Weakness : Each time you hit someone with your bomb, your allies deals more damage (3%) on him, now guess your bombs hit everyone :) Double Edged Sword is maybe useful for you but Expose Weakness is more powerful when you think to the team (3% for 4 mates is better than 2% just for you).

Natural Talent : AD + AP, let's go !

Oppressor : Your E is powerful, with Oppressor your Q is better.

Cunning

Wanderer : Movement Speed ! Go go go !

Secret Stash : Give that man a cookie ! Assassin is not for you, and you are not jungle to take Runic Affinity .

Meditation : Regen mana equals more bombs on the ground. Merciless will be Ok if you don't have any difficulty with your mana recover.

Bandit : Ambiant gold is low but useful.

Intelligence : Is an important mastery to reach 45% cooldown reduce !

Thunderlord's Decree : free damage :)

You should not be afraid to explain how work the combo of Zilean to your mate (ex. "Wait my stun before use your ultimate, that will be more powerful :) Trust me i'm an Zilean!" or anything else) if they are playing badly near you.

Jhin : Attack them, Jhin will be able to root them with Deadly Flourish, QWQ on them : free stun for you !

Lucian : Move speed is the key when you are playing with a Lucian, buff him and he will get the kill.

Caitlyn : When Yordle Snap Trap catch someone, QWQ him !

Kalista : Don't be afraid to use her ultimate ( Fate's Call), you'll survive ;)

Tristana : The ennemies will be suprised because both of your damage isn't instant, 2 bombs Explosive Charge & Time Bomb, 2 delay.

Miss Fortune : If you stun 1+ people, it's a free ultimate for her, then you can put the slow on the guys who you want to see dead. Enjoy.

PS : If you find any mistakes (language or something else, let me a comment :P )