Hello, my name is Lukresio and this is my first ever League of Legends Mobafire guide. I used Mobafire a lot when I started out and still do occasionally to get a good grasp on champions I do not understand. I have always enjoyed a better guide than a good build and that is what I am aiming for this to be. My guide is based off of what I know you will be able to do with the build I have recommended but there is more than one way to play Zilean but if nothing else people new to him will receive some good tips on how to play him.

Pros
Early game dominance
Great constant speed boost
Very good slow that is off of cool down very often
Great ultimate
Is not very farm dependent

Cons
He's old (unless your into that sort of thing. pro?)

The runes I take are to best fit my play style. I enjoy harassing but not wasting so I forgo taking MP5 seals as I used to and instead just go straight AP. Zilean can single handedly win your lane early game so I base my guide off of having a very strong early game. If your lane goes well, late game will be a breeze.

Marks: Greater Mark of Magic Penetration
My reason for taking these is simple, when you are playing to carry, penetration marks are in most cases the superior choice. Taking any level of flad AD, AP, Crit, or any damage related mark won't have a very signifigant impact due to starting armor/resist. Taking these penetration red makes sure that you get the most out of your remaining runes and starting items.

Seals: Greater Seal of Ability Power
Here is where I will understand if some people's opinions differ. The best alternative (which I have tried) to Potency seals is replenishment seals. If you spam your abilities constantly and double bomb without need you will run out of mana very quickly. When starting out, I do not believe it is a bad idea to run replenishment seals until you have how and when to use your abilities more under control.

Glyphs: Greater Glyph of Ability Power
These glyphs will make it to where you have no need to run out of mana quickly these glyphs, along with your quints, early magic pen, and starting item will give you a very nice amount of starting AP to start doing serious damage with.

Quintessence: Greater Quintessence of Ability Power
I just feel it gives you so much early lane dominance. There are other viable choice, but trust me, i've started with the wrong rune page before by mistake, and not having these runes seriously throws off the early game and majorly cripples the damage you will deal.

Pretty simple really. I'm sure pretty much everyone reading this has a similar one already set up with maybe slight differences in the exp boost in utility. If you are planning soloing mid, I do recommend taking the points in that instead. The only reason I take mana regeneration instead is because Zilean's passive eliminates any gap your enemy could create in a duo lane and with the more damage based runes it assists in having a more reliable mana pool.

I have tried countless starting items in numerous games and found Doran's Ring to be the all-around best starting item for this build. It gives better survivability, a decent amount of AP, and helps with the mana problems you could encounter.

I tried starting with a Sapphire Crystal and a couple of Health Potion. It isn't a terrible way to start, and is good to rush Rod of Ages but it doesn't give that nice damage that Doran's Ring does.

I also tried starting with Boots and a few Health Potion and Mana Potion and I would strongly recommend avoiding this. It does benefit in getting off bombs with a better chance of no counter attack, but it leaves you mana hungry and damage deprived. Also it doesn't really build into an item that is nesseccary for you to rush.

I tried Mana Manipulator I gave this one a try for a good while as it does cure mana problems early game and if you lane with someone else using mana it is a very useful item. However it builds into Soul Shroud and I usually only purchase this Soul Shroud if I know I will have very little impact on damaging the enemy team late game.

Typically when you go back for the first time , you will easily be able to purchase: Doran's Ring
Boots
A few Health Potion Mana Potion
And A sight ward or two. (Do this if the enemy team has a jungler)

The reason for purchasing another Doran's Ring is because it solidifies your lane dominance. You will be able to take more shots, do more damage, and replenish more mana.

The reason for Boots is for better mobility and being able to more easily double bomb with less risk of taking damage and to escape ganks.


Your next purchase will be: Blasting Wand
The reason for this is the build into Archangel's Staff shortly to rid yourself of mana problems all together and to continue your high damage output. If you achieve this on track you can easily take half of any non-tanky carries hp with a single double bomb.

Your next purchase will be: Sorcerer's Shoes
The reason for this is it is relatively inexpensive and you will most certainly be able to afford this on your next blue pill. It makes double bombing and escaping even easier and by this point if your lane opponets are smart they have gotten at least a small bit of magic resistance to better defend against you and this will make it that more insignificant.

Your next purchase will be: Archangel's Staff
I have only recently started doing this, but it works insanely well. I used to rush Deathcap, but I am actually able to more easily obtain Deathcap following building this item because I rarely, if ever, have a need to blue pill for mana. Zilean can be very reliant on blue buff but this eases that need substantially and gives a nice AP boost to better impact your upcoming Deathcap.

Your next purchase will be: Rabadon's Deathcap
Did someone say good game? You might as well. Your AP will skyrocket and it will be noticable to an unreal extreme when you double bomb your first squishy after having bought it. No major explanation needed for why you buy this item. You can let your bombs do the talking.

Your next purchase will be: Rod of Ages
The reason for buying this item is you are still squishy, and in team fights a wise team will focus you down even if you aren't playing well due to your ultimate. The longer you live the better off your whole team will be. It also completely takes care of any mana issues you will suffer for the rest of the game and gives you a nice AP boost along with it.

Your next item will be: Banshee's Veil
To be totally honest, you probably won't get this far very often, but your bombs are already extremely powerful and this just prevents you from having to worry so much about being CC'd in a team fight and failing your ult.

Your final item will be: Zhonya's Hourglass
Well with Banshee's Veil you have secured some magic resistance, but you're still lacking armor. Zhonya's Hourglass will take care of it and give the much unneeded AP boost. I will say however that both Banshee's Veil and Zhonya's Hourglass are reasonably situational. If the opposing team has no hard CC and there isn't a well fed AP carry there are much better items to consider. Also if the opposing team hasn't had any star AD carries mowing down your team then you're really just buying some really expensive AP. Also if they are being fed, then the order of the final two items can change. If their AD carry is being fed and the AP is left behind with little to no CC, rush Zhonya's Hourglass and vice versa.

Why Ignite and Flash?

Well Flash is pretty much locked in, if you don't play drunk (I know a lot who do) You will be squishy, even if you like the Rod of Ages + Rylia's Crystal Scepter route, that’s a nice amount of health that you will still be nuked into oblivion without armor and magic resistance. Flash is a great escape and comes in handy both offensively and defensively.

Ignite can be debated by some, but a first blood with Zilean is just far too easy when you carry this. On average I can drop any carry's health to low enough that a double bomb + Ignite will finish the job in 2-3 bombs. It is also arguably supportive when facing certain healing enemies such as Swain and Warwick.

Acceptable choices
Clairvoyance - You ARE a support, and in something like a ranked game this spell is very important. You will be the most qualified to take it sense early game you shouldn't be majorly farm focused anyway giving you more time for map awareness and assisting your team with this spell (If you do take this, I recommend getting it's buff in the tree though, at the cost of either point in the second leg of the utility tree)

Clarity - I highly oppose this, as you should not run out of mana to often without carelessly using your abilities. However if you are going to lane with a champion who you know uses mana reasonably quickly it is a very understandable choice and replace Ignite (as with any you would choose to replace) with this.

Teleport - I recommend taking this spell under one condition, solo lane. If you are not solo laneing then there is really no need for you to have this. You can get back to lane quicker than most champions so having Teleport is really not needed.

Cleanse - This spell is always acceptable. Many people just don't understand how great it is.

If vlad ults you, you cleanse and it's k.
Karth ult? You cleanse and it's k.
Oh no! Amumu, Nunu, warwick and Ashe all ulted us at once! Cleanse = k.
Hell it even cancels ignite xD

TROLOLOL
Brief explanations as they aren't worth explaining why.

Exhaust - You have your E, same thing minus the damage reduction, you should not stand and auto attack an opposing carry. Bomb + Slow + Rewind + Bomb = Profit. k?

Revive - The most OP summoner spell in the game bar none. (unless you count every other spell in the game)

Ghost - I would be tempted to put this as situational, or acceptable, but for zilean, this is over rated. This isn't a rammus land speed record guide to see if your boots of mobility, 5 phantom dancers, and E can get you over 2000 movement speed. End game, with blue buff, you can have you E on (with rewind being used) seriously at all times. With that being said, no one is going to catch up to you and you don't need ghost to catch up to anyone.

Smite - If you jungle Zilean, much respect. If he weren't so squishy and had a little more AD or AS, I think it could be viable.

Fortify - Well, tower diving you would pretty much be guaranteed suicide now. Acceptable as support, but this isn't a straight support guide.

Heal - I just don't think it's worth it late game and it's nice to bait with but zileans' not really consistent damage. He's more there goes half your health in .5 seconds, I’ll do it again in 8 seconds if I live that long.

First of all, I prefer to play Zilean in a duo lane. He is a good solo, but I feel a large portion of the outcome of a game comes from the duo lane as when at least one person of common sense if in that lane it is less likely you feed two people and as Zilean you can make it very easy for the opposing laners to be unable to reach your lane partner all together.

So now that you have bought your Doran's Ring head to bottom and as long as you didn't take forever go ahead and wait in the first brush as close to your tower as you can get while still being inside. The reason I do this is if the enemy facechecks the brush I will:
A.) Know who my lane opponets are.
B.) Be able to decide how my lane opponets are going to build.
C.) Go ahead and drop a bomb for the hell of it if they are melee carries.

Following that, if you are alone, retreat to your tower and await minions.

Now as Zilean, you must remember that early game you will be mana hungry and bombing every minion wave will be a total waste of your mana. The best thing for you to do as Zilean is use the brush and do the following:

When the enemy pushes forward you take a step out, place bomb, step back in brush and repeat constantly. This will prevent the opposing lane from farming and get them low quite fast for your first kill.

I prefer to let my lane partner take all of the minions he can. If he is simply auto attacking and not trying to last hit I instead take as many as I can (with auto attacks only) When you have gotten an enemy to around 33% of their HP (depending on the enemys total health and MR) This is the combo I use to finish them off:

E > Flash > Q > W > Q > Ignite

You may use the E on your enemy if they are close enough of yourself to ensure you land all of your abilities before they are able to escape. If Flash is not needed to close the gap, don't bother wasting it.

Now you can farm with your bombs! Now a very important thing to know is when your typical enemy minion wave is approaching you do not double bomb the very first minion that reaches you. The proper way to farm with bombs on a typical approaching wave is to let the minions reach you so they are all set and get the full effect of your bomb.
Place one bomb on one of the 3 melee minions and one bomb on one of the three caster minions. Your goal is to get the area of effect on the explosion of the bomb to hit as many minions as possible. Until a little later the melee minions will not die to this one bomb and while you await the detination of your bombs you should equally spread out auto attacks among the melee minions. The caster minions however will die to a single bomb with a relatively low amount of AP.
So when bombing minions your auto attacks focus should be:

Cannon Minions > Melee Minions > Dont even worry about caster minions

I will first say that at this point it is likely very large groups of minions have started pushing towers, in this case, you do not have to seperate your bombs when 10+ minions are clustered. You can instead double bomb a single minion and in most cases of these large waves no more than 2 or 3 minions will be left afterwords.

Now team fight will start to decide the fate of the game. You NEED to be there for team fights. Always mark who your dominant carry is before you are thrown into a team fight. It is very likely that player will be heavily focused and if they aren't there is an even greater chance of you winning your team fight. I know it's heartless, but if the fight isn't a sure thing that you are going to win don't waste your ultimate on that 2/11 Master Yi when your 14/4 Vayne is already half health. Saving players with your ultimate that aren't really able to contribute in a team fight over those who are able to cut down everyone on the enemy team is not worth it.

My final recommendation, try to learn smartcasting. Sense this is my first guide I would greatly enjoy constructive critisism on anything you enjoyed or didn't enjoy about my guide to help me to better produce any future ones I decide to make. So please don't just downvote and not explain why you disagree. Any suggestions are welcome, Thanks =)