Because im not very good with math and dont have tons of free time this guide is still a work in progress. By work in progress Im talking about the actual guide section not the Runes/Masteries/Items selection. I need to figure out the actual numeric values of my build to better explain why/how I use it. So If your good with math please stop by the Forums and help me out a little.
Dammit they jsut changed Zil specs a little so now i need to redo all my math...stay tunned

This is my Zil guide. Ive been using Zil a long time now and have gotten pretty good with him in my opinion. I prefer Ability Power over Cool Down Reduction. But I still mainly play as a support. But even though I play a support role I still am very aggressive and dont buy supportive items. Its just that im a support Nuke. Come on...whats not to like about a reviving A-Bomb that's gives you speed boots and Bonus EXP.
Im writing this guide because the best guide I found on Zil is all about CDr and I wont deny that is a killer guide/build and it helped me learn how to play Zil, but switching to pure AP is what led to me being a more useful support in relation to my style of play. I don't intend or think this guide will ever trump Tr4ce's CDr guide but I do hope it will be the best alternative.

Abbreviated Terms
AA = Auto-attack (Basic Attacks)
CC = Crowd Control (Stun, fear, slow, snare, etc)
FB = First Blood
AP = Ability Power
AD = Attack Damage
MD = Magic Damage
AS = Attack Speed
MS = Movement Speed
MR = Magic Resistance
ArPen = Armor Penetration
MPen = Magic Penetration
LS = Life Steal
SV = Spell Vamp
DPS = Strong Auto-attacker
MDPS = Strong spells; casters
CDR = Cooldown Reduction
OOM = Out of Mana
MP = Mana
HP = Health
MP Regen = Mana Regeneration per 5 seconds
HP Regen = Health Regeneration per 5 seconds
ULT = Your Ultimate Ability (Usually is available at lvl 6)
Rez = Resurrection (instant Revive IE. if someone is Rez'd they come back to live with out getting a death point and the killer dosent get a Kill Point)

For me this is the only worthy Skin choice of Zil
Image by guardjung

Potency Runes vs Force Runes

Potency Runes give a flat bonus of 34.41 AP if you fill your whole Rune page with em which is amazing early game.

Force Runes give 4.62 AP every lvl maxing out at 83.16 at lvl 18. By lvl 7 you have matched the Potency Runes. Seems like a no brainier to me.

My Masteries are 9/0/21

Offensive = 9

Teir I

Archmage's Savvy - 3/3
That gives you 10.8 more AP at lvl 18. This build is all about how much AP you can get.
After Archmage's Savvy its a matter of play style for your next one point

Teir II

Sorcery - 4/4
This is for your much needed CDr. Even though this is an AP heavy build CDr is very important with Zil

Teir III

Archaic Knowledge - 1/1
This one point can help alot early game when people can only afford a Null-Magic Mantle and more so later in the game incase you need to buy a Void Staff

Utility = 21

Teir I

Perseverance - 3/3
You need that 4% Mana Regen early game
The other point on Teir I is a matter of personal choice and play style

Teir II

Awareness - 4/4
5% exp boost + your passive Heightened Learning = +13% exp boost in game...not to bad if you ask me.

Expanded Mind - 3/3
Im trying to figure out how much mana this gets you as well as the bonus effect you receive from Archangel's Staff but basically this is needed for getting as much AP and mana as possible.

Teir III

Meditation - 3/3
You need this 5 mana per sec early game.

Utility Mastery - 2/2
This is for the Mana Golem/Blue Buff and Baron Buff.
Blue buff lasts 2 1/2 min's, or 150 sec's. This increases to 195 with the mastery, an increase of 45 sec's.
Baron lasts 4 min's, or 240 sec's. This increases to 312 sec's with this mastery, an increase of 72 sec's


Teir V

Intelligence - 3/3
This combined with the Sorcery Mastery gives you 9% CDr right from the start.

Teir VI

Presence of the Master - 1/1
This is needed to speed up the CDr of your Summoner Spells

My Spells
Revive is a misunderstood Summoner Spell. A common response when I get Revive is "So uh Zil you plan on Dying?" to which I say "Yes I do...unless of course you want me to always save my ULT for myself" As an added bonus when you use Revive your Movement Speed gets an enormous boost for a few sec's. This combined with Time Warp +Rewind can get you back in the fight in under 3 sec's so long as you dont have to run to the other base...in which case your looking at 4-5 sec's to get there. Also your now able to freely us Chrono Shift when ever you want. Yes you can still die but 2 or 3 deaths isn't a big deal if you only miss out on some action for a couple sec's.
Clarity is so you can use your mana all willy nilly. It also helps if someone on your team needs mana. Be sure to say something to you lane partner if you want to use it soon so they can pop off a few spells if their mana is full.

Other Options
If you really dont want to use Revive or Clarity then try these other useful spells out.
Clairvoyance is helpful for avoiding lane ganks
Cleanse is great for getting rid of Stun or Taunt
Exhaust is good for offense and defense. And is you ad the Mastery Point to it it only gets more effective.
Flash is great for getting away or popping in on someone.
Fortify can help you land a kill or two early game if someone is to hungry but other then that I see no real need for it on Zil.
Ghost is an amazing Spell on Zil. If you swap Ghost for Clarity you can die at the enemy base and get back there in under 3 sec's so long as Time Warp and Ghost are ready. That also mean you can catch who ever killed you pretty much no matter where they are on the map.
Heal can save you from wasting your ULT on your self or a friend. For me its not to useful but Im sure it can have its moments.
Ignite could help you land kills very often where your bomb's leave the person with just enough life to get away. And if you give it a point on the Mastery Tree you get some bonus AP which is always good early game.
Rally is really only good if you post it during team fights and use it to drop bombs on to. Pretty much dont waste your time on this spell if your going with my build.
Smite makes getting the Mana Buff so much easier. And with the point from the Mastery Tree you get a little more gold for using it to last hit stuff. Not a bad spell if you make good use of it.
Teleport is only good to get to lane ASAP so you can Farm a huge wave of minions...honestly this is just one more spell you dont need with my build.

Core Items

There are 3 items needed for this build. Everything else is optional and or interchangeable


Tear of the Goddess should take 15-20 min's to get the max mana out of it. You get 4 mana per spell cast. so that means you have to cast 250 spells to max the mana. Thats like one spell every less then 10 sec's. You should have this item before you hit lvl 6. If you dont you better get it right after.

Rod of Ages should take around 10 mins to max out once youve completed it. This is why I get the Tear of the Goddess before. Plus this will max its self out weather your alive or dead with no effort at all.

Rabadon's Deathcap is explained in more detail in the Ability Power Section.

Movement Items

When it comes to your boots you should only need to pick between 3 based on needs of the game. Personally I only use Ionian Boots of Lucidity because of the CDr boost but I know people like the ability to try other things.

Ionian Boots of Lucidity are my boots of choice 98% of the time. I love the 15% CDR.

Mercury's Treads are helpful w when you cant afford time to be stunned or taunted...cause if your stunned or taunted you cant use your moves which makes you the most useless Champ in the game for all of 1-3 sec's. Only buy these if you are Target Number I and your team is doing diddly squat to help you.

Sorcerer's Shoes are only useful if you need that little bonus to MPen. Personally Id prefer the 15% CDr or 35% duration reduction to stuns and taunts.

{b]The other Stuff[/b]

UNDER CONSTRUCTION

In this section ill further breakdown and explain how to get the 1K+ bomb Damage this guide was made for. To do that you need two things.

Ability Power + Mana

You need lots of mana to spam ability's as much as possible. Also because of Archangel's
Staff the more mana you have the more AP you gain from it. Now add this to the Rabadon's Deathcap and now the more AP you have the more you gain. So my Idea was to gain as much Mana and AP with as few items as possible as fast as possible.

Rabadon's Deathcap will give 155 AP at item completion.

Archangel's Staff will give 117 AP by default once its completed. Thats 45 AP for the item and 72 AP because it gives 1400 mana for the item and a bonus 1000 mana from maxing out Tear of the Goddess

Rod of Ages takes 10 min's to max out. Once its done you now have 925 mana and 100 AP

Archmage's Savvy Mastery gives you 10.8 at lvl 18

Expanded mind Mastery gives you 670 bonus mana at lvl 18.

Default Mana at lvl 18 is 1340

Force Runes give 83.16 at lvl 18

Lets add you mana first
670
925
1340
2400
----
5335 Mana at lvl 18. With Archangel's Staff you have 160.06 Bonus AP just from 3% of your mana

Now lets add our AP and see where were at
10.8
45
83.16
100
155
160.05

---

714.06 AP. 30% of that is 214.218. So you now have 928.278 from just your Runes, Mastery's, and 3 Core Items

Now if you get far enough along to pick up Morello's Evil Tome you can add 75 AP. And if you get the Baron his Buff gives you 40 AP for how ever long the buff lasts. Whit these all together that brings a grand total of 1043.278 AP.

Now why do we need this much AP you ask...well ill tell you

Time Bomb does 330 Damage at lvl 18. Add 90% of your AP and now you do 1268.95 Damage Per Bomb. With the basic Zil combo that means you can deal 2537 Damage in under 5 sec's. Not to bad for a support.

Chrono Shift gives 1000 Health on Rez once its maxed out. With you Current AP you now Rez people for [4806.85[/b] Health...Thats nearly full life for most Tanks.

Max CDR is 40%.

Blue buff gives you 16% CDR plus 0.5% CDR for every level you have.

Ionian Boots of Lucidity = 15% CDR

Morello's Death TomeMorello's Death Tome = 20% CDR

Sorcery Mastery = 3% CDR

Intelligence Mastery = =6% CDR

Now not counting the Mana Buff you have 44% CDR total...which means with the full build you are wasting 4% CDR which you can easily cut off by chopping two points off of the Intelligence Mastery. If you do that you will Perfectly max out at 40% CDR if you have the two CDR items.
But isn't that 9% CDR right out the gate nice, Yes...Yes it is. And what do you do If you can make the Full Build or heaven for bid swap a CDR items for a MPen item...now you'd wish you still had that full 9% CDR.

Things im working on
Farming
Ganking
Laneing
Finishing the Items Section
Pros/Cons
Skills
MORE NUMBER CRUNCHING
Early/Mid/Late Game sections
Hopefully a few Videos about Zil
Some end game result Screen Shoots
A Thank you Section