1) READ ALL THE NOTES, THEY'RE VERY IMPORTANT.
2) This is a build that can only be used in high elo because if you try to use it in low elo you'll be useless. This is a utility pick so you need a good team to play with, you're warned.
3) This pick is hard to dominate so don't try to use it in ranked games at once, first try this champion building him AP and when you completely understood it you can use it with this build.
4) You have to trust in your team and they have to trust in you, this pick depends 90% on how much your team takes advantage of the opportunities that you give them. If you have a team that don't know how to follow you, you'll lose your games.

Pros:
-You are a ranged champion so you have advantage against almost every top laner.
-You are playing a champion that it's not broken so you don't have to worry about nerfs.
-You can initiate teamfights very easily.
-You are very usefull for your team.
-You can be used as a second support or even a bait to start fights.

Cons:
-Horrible basic attacks animations that make it difficult to farm in lane.
-Less damage for the team.
-You need a good team to play with.
-Even if you're building as a tank, you don't resist too much.

This build was made to work with the Kleptomancy, and the way that you use it will define your utility in all the game.
When you are in lane, your mission is to use the Kleptomancy as much as you can because your champion has everything to abuse of this. You can use the combo E + AA + W + AA + E + AA to use the Kleptomancy 3 times with this combo and get a lot of gold selling the useless items. Remember that the Kleptomancy has a cooldown that is not established so when you do the combo try to give 1 or 2 seconds every time you use an ability to be able to activate the Kleptomancy.

You have to know that you're not going to make any damage to the enemy team in the late game. You are completely utility for your team, if you know that you are building as a tank, you have to start teamfights as one. Take a Maokai as an example, he goes 1 vs 5 to trap one of the enemies and let his team take the kill, the same case when you're playing Zilean. You don't have to be scary, ¡YOU HAVE 3 LIFES! start teamfights whenever you want, but be sure that your team will follow you because if they don't... you'll be useless.

1) Don't make an innecesary poke, you only want to use the Kleptomancy so don't try to make long fights because you'll lose farm (only poke if you're sure that you can kill the enemy).
2) Use your ult in an intelligent way. For example, if you are in lane and you have your Guardian Angel don't use it, better use your ult because the Guardian Angel can save you and also the ult have less cooldown. But if you're in teamfight, you better don't use your ult in you, because if you are playing to help the ADC or some powerful member of the team, it is better to wait to use it on him. The case is other if you are playing in front lane when you are in teamfights, in this case you will have to ult yourself because you are all the CC of the team and you will make impossible the life of the enemies.
3) Play as if you were an ADC, keep a lot of distance between you and your enemy because if you make a mistake, you can die very easily. Remember that you are one of the champions with less armor in the game.
4) Don't use too much mana, always safe some mana for the ult because you don't know when the jungle is going to come and try to dive the tower.
5) Use the combo Ctrl 6 + Ctrl 4, this will help to tilt the enemy and make him want to kill you and you will take advantage of this.
6) Ask your jungle to gank you a lot. Zilean is a champion that has a very good damage in early and a lot of CC so if you tell the jungle to gank you, it's 99% probable to take a kill or at least make the enemy use flash.
7) Please, DONT STEAL THE KILLS. Your are as a second support for the team (but better) so you have to make sure that your team gets a lot of kills and you'll only have to help them to survive to teamfights and give them oportunities.
8) Sell everything that the Kleptomancy gives you except the health and mana potions.

This build is ready to be used, but I have a lot more things to say about it to make all of you play it correctly.