Hello there, this is a build I want to share with you guys. Many people that play with me know me for my ad zilean; note: i play it at 3v3's, 5v5's get more complicated to succeed. Zilean is by far one of the greatest AD carries in the game, he has one of the longest ranges, and get this, his base ad at lvl 18 is greater than Ashe :O
Anyways, the rune page i put up there is not necessarely the best for ad zilean, but it is the one i use. i would think attack speed and crits would do a better job at aiding you to get kills early so you can get fed trhoguhout the game more than the runepage i posted, but full attack damage with armor pen also helps.
his build depends entirely on attack speed, crit chance and damage, added to it of course, lifesteal from the bloodthrister.
It is always fun to walk into a champ select room and announce "AD ZILEAN!!!!" and have that one smart*** that says "I will report you if you go ad", next thing you do is lock in, "troll face". After the game starts, the raging continues untill at some point in the game, they realize that they only survived a certain teamfight because you revived them and then proceeded to aqcuire a triple kill.

Next you will see some more details of my choices and decisions while playing ad zilean

Many people will not think AD Zilean is viable at all, so I decided to post a little table with some ranges and damages in the game:

650 range:
625 Range:
600 Range: , ,
575 Range:
550 Range: , , , , , , , (625 at lvl9 and 700 at lvl 18)
525 Range: , ,
510 Range:
500 Range: , , ,

112 -
110.7 -
108.5 -
108.26 -
105.81 -
102.6 -
102.2 -
101.2 - ,
101 -
100.5 - ,
100 -
98.5 -
97.6 -

Looking at these stats, it becomes obvious that zilean beats many ad carries in both Damage and Range which makes the AD Zilean build very reliable

The runes' total focus is the ability to deal the most damage possible with each blow, so the rune composition is as follows:

Greater Mark of Desolation- This rune is going to add that armor penetration you need to deal tons of damage to tanks during an early game

Greater Seal of Attack Damage, Greater Glyph of Attack Damage and Greater Quintessence of Attack Damage - These runes are there just to add flat damage since Zilean is not really supposed to be ad, he doesn't have many abilities aiding that purpose

What is my reasoning behind my mastery choice?

Well, the masteries I pick support the concept of dealing tons of damage while adding some meat to my champion's health with a little extra armor, magic resistance and health regen

Here is the mastery composition:my enemies out of lane faster therefore extending the lvl difference as well as the gold difference between my enemies and my team

My choice of items focuses basically on attackspeed and crit, these combined will crush your opponent when you slow him down, so that pretty much explains your Phantom Dancer, your Berserker's Greaves and your Infinity Edge.
Also to help you win battles, there’s this underrated item, the Youmuu's Ghostblade, it gives you some crit and some damage as well as some cooldown reduction for your spells, and it also has that active that increases attack speed and movement speed, these buffs are very important for Zilean during early game because it will give him a tremendous advantage.
Bloodthirster is fundamental because of the huge advantage provided by the high life steal and damage, so after a rough fight you don’t have to stop farming to heal back up
Nashor's Tooth has ability power, attack speed and cooldown reduction. Why an item that has ability power? Even though we are technically playing ad, at late game, some opponents realized that you are a killing machine and will take precautions like getting thornmail, and such, the Time Bomb will now be stronger than before adding a little more burst so that you can reduce their health while you wait on reinforcements. That cooldown reduction will really be useful since it will make your Chronoshift cool down faster.

Another option with less attack speed and ability power is the following:

The only reason you want to build this way is if you have a very tough tank in the enemy team of course, but there are multiple combinations possible, there is no telling which one would be the best.

- This ability can place a bomb on either enemies or allies, once the carrier of the bomb dies, the bomb detonates, or after a set time

- This ability cools down your abilities by 10 seconds, you can use this to place 2 Time Bomb on your enemy, and if your cooldown reduction is high enough, you can constantly use Time Warp

- This has 2 different effects, casted on an ally will increase its movement speed for a set duration while casting it on an enemy will reduce its movement speed for a duration

] - This ability allows you to bring an ally or yourself back to life with a set ammount of health and mana, ultra useful if used with Guardian Angel

My skill sequence is focused on your Time Warp ability, it has a long cooldown but the more you level it up, the longer it's effect will last on your targets.
Although your Time Bomb is the first thing you get, you dont level it up anymore until you're done maxing your Time Warp, but if the situation calls for earlier upgrades on your Time Bomb, that is ok too.
The tricky part is that your Rewind has a shorter cooldown the more you upgrade it, so you really want to max that out second, and whatever ability you leave as your last option will be upgraded only when all of the others are done maxing out.
Your Time Warp is key to winning, your enemies will turn around and try to escape but they will not be able to move too far, while they try to flee you can keep hitting them with your autoattacks and drop the double bomb on them as soon as they out of your reach

The Combination I use is:

*lalalala walking in the jungle* OH, ENEMY SPOTTED, HEY WHERE ARE YOU GOING Time Warp, autoattack attack attack, Time Bomb, Rewind then Time Bomb Agin! (he would probably be dead before you even rewind)

Recommended
Flash - it will save you from ganks
Heal - will keep you in your lane for a longer time
Clarity - if you realize your low on mana when you need to use Time Warp this can save your ***
Ignite - might deal the extra damage necessary to get you the kill

Might work
Clairvoyance - supports are more likely to carry it, since you are a support.. kind of says you should use it
Cleanse - might save you from that annoying stun or silence that would cost you your life
Ghost - I feel like it is useless, but in rare occasions it can be your ultimate salvation
Surge - never really used it but might be useful early game

Useless
Teleport - since this build works better at 3v3's, this spell really has no use
Revive - come on, if your Chronoshift is not good enough, you really need to practice more
Exhaust - built in slow is already good enough
Promote - can be good when you leave the lane but you really need to use your summoner spell slot to defend yourself as a champion than the whole lane
Smite - you are not jungling

Pros

Great at 1v1
His range is longer than most champions in the game
He can take on any champ, revive yourself, and finish killing him if necessary
Can run from ganks
When people overextend to finish you off, you can just slow them down at turret range as they approach and use your ultimate

Cons

Will not survive a 3v1 (when teams are pretty even)
Takes a while to start feeling like you make a difference
A lot of your AoE is lost since you dont have that much power with your bombs
Becomes useless when it is late game

One good strategy is to run around with another teammate, using your Time Warp on an enemy that you see, and I swear you will ALWAYS kill them. That will help you gain gold faster and give your team the edge.

Also, make sure you are last-hitting the enemy minions, since you are going against the natural flow of the champion, you will need the items fast so that you can even have a chance

Please active members of mobafire if you thought I did a good job in my guide, if you don't agree with something I said or you just want to ask a question, please pm me.
I will always be willing to discuss details about the build with the intention to improve it but I need your help to do some of it. Also, please don't forget to rate and comment my guide, I have put a reasonable ammount of time into this guide to deliver you a decent piece of information about Zilean and seeing that people like it and comment on it motivates me to do a better job!!

Thanks to all of you that have seen my build, and super thanks to the people that commented and rated I very much appretiate it

Thanks to JhoiJhoi! Her epic guide can be found here!

Thank you thank you so much!!!!

Also special thanks to Muukzor, your PM's with some ideas helped me improve my guide!!!

04.06.2012 - Added the Update, Range/Damage and Extra Info Chapters.

04.11.2012 - Added some more items to the "Extra Info" Chapter, fixed some logo typos and added the Take Action Chapter and added patch notes.

Also in here:

v1.0.0.134 - 2012-02-14

Fixed a bug where Chronoshift could prevent a clone from expiring, allowing them to survive indefinitely until killed

v1.0.0.116 - 2011-04-25

Revised Zilean's idle animation loop
Fixed a bug where Zilean's Chronoshift would sometimes not report to allies whether it was castable

v1.0.0.113 - 2011-03-15

Time Bomb
Mana cost increased to 70/85/100/115/130 from 60/75/90/105/120
Base damage reduced to 90/145/200/260/320 from 100/155/210/270/330
Chrono Shift
Base revive increased to 600/850/1100 from 500/750/1000
Ability power ratio reduced to 2 from 3
Buff duration reduced to 7 from 10

v1.0.0.112 - 2011-03-01

Fixed a bug where the particle on Time Warp would not persist through the full duration of the movement speed modifier at later ranks

v1.0.0.111 - 2011-02-16

Base magic resistance reduced to 30 from 35

v1.0.0.109 - 2011-01-17

Chronoshift duration reduced to 10 seconds from 13

v1.0.0.103 - 2010-10-18

Chronoshift now removes most positive buffs from your champion when it activates. For example, Soraka's Astral Blessing, Garen's Judgment, and Fiddlesticks' Crowstorm will now be removed.

v1.0.0.101 - 2010-09-21

Chronoshift duration reduced to 13 seconds from 15
Chronoshift cooldown increased to 180 seconds at all levels from 180/160/140 seconds

v1.0.0.97 - 2010-07-27

Chronoshift's buff icon will now display a timer for when the buff will fade.

v1.0.0.96 - Season 1 - 2010-07-13

Fixed a bug where replacing an enemy Time Bomb wouldn't cause the deactivation explosion
Fixed a bug where replacing your own Time Bomb caused more damage than intended from ability power
Fixed a bug where the Time Bomb explosion particle occasionally showed over fog of war
Fixed a bug where Time Bomb would occasionally remain on dead units

v1.0.0.87 - 2010-06-08

Clarified Rewind tooltip to remove some redundant information

v1.0.0.86 - 2010-06-01

Timebomb Ability Power ratio decreased to .9 from 1.1
Timebomb now ticks 3, 2, 1 additional damage before the bomb explodes. This will trigger calls for help

v1.0.0.79 - 2010-03-16

Fixed a particle issue with Time Bomb

v1.0.0.74 - 2010-02-10

Rewind Cooldown reduced to 18/15/12/9/6 from 30/28/26/24/22, but will no longer affect itself

v1.0.0.72 - 2010-02-02

Time Warp Movement Speed modifier reduced to 55%, from 65%
Time Warp's haste effect is now a multiplicative movement speed modifier
Time Warp duration reduced to 2.5/3.25/4/4.75/5.5, from 3/4/5/6/7
Time Bomb and Time Warp range increased to 650 from 600.
Chronoshift range increased to 900 from 600

v1.0.0.70 - 2010-01-13

Time Warp now applies a multiplicative movement speed slow rather than additive.
Rewind Cooldown changed to 30/28/26/24/22 from 38/34/30/26/22
Time Bomb Damage increased to 100/155/210/270/330 from 90/145/200/260/320
Time Bomb Mana Cost decreased to 60/75/90/105/120 from 70/85/100/115/130
Time Warp Mana Cost decreased to 100 from 110 at all ranks

v1.0.0.63 - 2009-12-17

Basic Attack Projectile Speed increased to 1200 from 900

v1.0.0.61 - 2009-12-02

Time Bomb no longer detonates if the buff is cleansed