Why Zilean? and Where?
Zilean can do 3 roles, He succeeds MUCH better by himself, this build in particular is Zilean Top/Mid, but he can also play support. Using this build, you will find that Zilean can not be beaten in lane... it's impossible.

Mana Regen, because bomb/rewind/bomb two times and you're oom.
Ability Power, B2Bombs need that kick to slay them hoodrats
Magic Pen, This one is very important because those bombs get shut dowwn HARD by stacking magic resist

These are my basic ability power mastery build for zilean, I use it for other champions also, but it was built around Zilean and Fiddlesticks, you can diddle with it if you want to, if you think you see something you like better, but I prefer it this way (:

We Start Mana Crystal for the extra Mana so you can keep in lane
You get a Health/Mana so you can stay, even with the crystal that mana is going to drain like nobodies bidness
You want to start at building a tear of goddess ASAP. It is what sets aside the okay zileans from the game changing ones.
Get your boots, start working on that rod of ages, IMO one of the most useful items in League Of Legends, it's got everything you want for your AP carry
Once you got this you should work on your rabadons to capitalize on that Ap damage
Now we start working on OP MODE, just get 2 more archangels, using this build i've got my AP up to 1300, doing 1.6-1.8k bombs per bomb, I was one shotting the carries.

Bomb first, why? cause thats your only attack. Then you max out bomb everytime you can put a point into it, do it, except at 6,11,16 of course.
Rewind, 2nd, because you need it to come off cooldown quicker, not only to bomb/rewind/bomb faster, but incase you're in trouble to speed boost away, also you can spam it to raise your mana points from your tear, AND lower the cd on your ulti
The speed boost is a nice get away or a helpful engager, but its the least of your worries

There is a VERY good reason I choose flash/ignite.. its called first blood.. almost everytime I get the first blood doing just this, try and try getting a bomb on them, if you manage to get them at half hp, and your level 3, level 2 bomb, and 1 rewind point, walk in bomb, flash forward while rewinding, bomb again,ignite walk away
first blood, everytime it's so cheap, its basically like ryze's flash ignite combo.

It works wonders, not many people do this in ranked, im at 1800 elo, playing Zilean top/kennen/urgot and eve, I've lost with Zilean maybe once of the 20 times i've played him ranked. Last game was 4-0-1, they surrendered. I was mid. People don't know what to do against, Zilean, he outranges mostly everyone, can do intense damage at early levels, and can revive people, he's SOO useful

Pro's

Almost completely unabled to be tower dived
Insane Early Game(And with my build great late game)
Piss people off with your ult
Fun and Easy to Play

Con's

Sustainable to ganks before level 6
Die's quickly to Burstfire, Veigar/Leblanc
Magic Resist really Kills him

Zilean is a VERY VERY viable top, this build works like 95% of the time, his counter are anyone that can burst him down really really fast, early game noone can really do that, that is what makes him so unstoppable, I recently fought xin zhao top with zilean, I crushed him, he kept leaping forward, i would bomb, slow, bomb, and walk off. Even once someone gets the burst damage needed, you can just tower hug, and bomb minions for cs, if they tower dive, bomb the **** out of them and get ready to ult yourself, he really is a perfect top. I hope my guide have been informative, I'm new to mobafire, and am just learning how the guide system works, if you want to help me make the guide better, or have comments or questions, feel free to leave, them and Have Fun pissing people off with the annoying Zilean Build i've discovered.