Zilean the Chronokeeper

Spells:

Timebomb (Q Skill)- Places a bomb on an individual target that explodes after 4 secs. At explosion, the bomb deals 80/140/200/260/320 dmg to a small area around the bomb. This spell costs 80/ 95/110/125/140 mana. Every ability point added is one point more damage. It's a 1-1 ratio of ability point to damage. The cooldown of this ability is around 10 seconds without buffs. 

If the enemy that is “Timebombed” dies before the bomb explodes, the bomb instantly explodes upon their death. Same is true if another timebomb is cast on an enemy around “Timebombed”

Opinion- This is the only offensive spell the Chronokeeper knows. You will use this spell more than any other spell in your arsenal. It is a very effective farming spell once you getting into the later levels and have stacked on some ability points. This is also a good harassing skill against champions in the early levels. 


Recall (W Skill)- Shortens the cooldown of all Chronokeepers spells. Costs 50 mana at all levels, and shorts the cooldowns by 10 seconds at all levels. Gaining levels in this spell shorts the cooldown of Recall to 40/35/30/25/20 secs each level.

Opinion- Recall is great especially if you want to spam Timebomb against different champions. It also reduces the cooldown of Time Warp and even your Ultimate. Since the mana cost doesn't scale with level, this is a very viable skill from early game to late game. Just be sure to keep an eye on your mana early game to not use too much mana to not have enough to cast the spell you wanted to cooldown.


Time Warp (E Skill)- Time Warp slows enemy champions or minions by 65%, or speeds up friend champions or minions by 65%. This effect lasts 3/4/5/6/7 secs per level. This ability has a 20 second cooldown every level, and costs 110 mana every level as well. 

Opinion- Nothing is more satisfying than slowing a champion down to meet his or her's untimely death (no pun intended). This ability has two main uses, and trust me they are handy. Time Warp is useful to slow down a fleeing champion, or slow down champions when you yourself are fleeing. However, this spell also has the benefit of speeding up fellow champions (or yourself) if they are chasing a fleeing a champion or fleeing from champions chasing them. If you are confused by that big mouth of a sentence, then just know that your fellow champions will be most appreciated when you cast this on them while they are running. 

Timewarp is also good mode of travel at end game when the cooldowns are low. 

Chronoshift (R Skill)- Ultimate!! Chronoshift is a spell that creates a 15 sec buff on yourself or a friendly champion that restores yourself to 500/750/ 1000 Health if killed while the buff is active. This spell costs 200 mana at all levels, and cooldown is 160/140/120 secs each level respectively. Any AP adds one health point per ability point. So if you have 130 AP and you cast the level 3 Chronoshift, the target will revive with 1130 Health.

Opinion- This is probably one of the main reasons your fellow champions love having you around. This ability allows your champion to live longer, and usually is used to save fleeing champions. Just know this, that if you are fleeing from two or three champions and they are about to kill you, unless your comrades are around, using this skill could be a waste. It takes a few seconds for you to come back to life, and usually your pursurers are surrounding your body waiting to kill you once again. Just be sure to use this spell wisely.

Heightened Learning (Passive)- Increases exp gain by either 3 or 4%. This is beneficial to all your friends and give you that slight edge again your opponents......unless they have a Zilean too.....

Recommended Skill Leveling
Level 1: Timebomb (1)
Level 2: Recall (1)
Level 3: Time Warp (1)
Level 4: Timebomb (2)
Level 5: Recall (2)
Level 6: Chrono Shift (1)
Level 7: Timebomb (3)
Level 8: Recall (3)
Level 9: Time Warp (2)
Level 10: Timebomb (4)
Level 11: Recall (4)
Level 12: Chrono Shift (2)
Level 13: Timebomb (5)
Level 14: Recall (5)
Level 15: Time Warp (3)
Level 16: Time Warp (4)
Level 17: Time Warp (5)
Level 18: Chrono Shift (3)

Reasoning Behind Leveling Guide:

Early-Game
Your first thought might be.....why aren't you leveling Timebomb to level 5 as soon as possible. Simple answer would be, because of mana cost. During early game, your mana is limited, and by raising the level of Timebomb you raise the damage, but lower the amount of times you can cast the ability.

Learning all three spells are beneficial for early game, especially when aiding your allies. During early game, use timebomb sparingly. Wait for the right moment to work together with your partner or fellow champions to use Time Warp to slow the enemy champion and then pounce. 

Mid-Game
Zilean's Timebomb will start to hit harder especially on champions with lower health (Ashe, Ryze, Veigar, etc...). Most of your kills will probably come during this time, but just because you get more kills does not mean you should start feeling “frisky”. Patience is golden, my friend.

Mana should be more managable now that you have more mana regeneration and more mana in general (More about this in the Item Build Section). Keep an eye on your mana to be sure to have enough to do your Timebomb-Recall-Timebomb spam (TRT). 

End-Game
With melee champions gaining more hp, your role takes more of a passive one than active. That's okay though....you're a support character not a death machine. Focus more during end-game on helping allies, but don't hesitate to do your trusty TRT combo to help out. 

Nearing end game, once you hit level 5 Timebomb and have raised your AP a bit, you can now one Timebomb minions, and this makes a great farming tool. Use Timebomb to help push lanes. 

Summoner Spells Recommendation:

Smite- Wait a second, Ryoshi! Smite is mostly used for Jungle levelers! It's horrible end-game! 

Not so, random yelling beta tester. Smite gives you the opportunity to have an instant nuke in timebomb. Remember early when I mentioned that if a minion or champion is killed while having that floating timebomb over their heads, the timebomb will explode instantly? Well apply that concept to smite. Smite allows you to put a timebomb on a minion and then smite him to death, giving you an instant nuke. Handy indeed!

Flash- Flash is by far my favorite escape tool. As Zilean, you will find yourself overpowered on many occasions. I remember there have been plenty of times that I have saved a fellow champion and then remembered, “Oh crap....they're coming after me now!” Flash gives you a chance to get right out of their range. It helps to avoid Viegar's prison, or to bypass the Cryophoenix's Ice Wall. This spell is a must.

Heal- Well if you can save your allies from death, you might as well be able to heal them. I can never think of a bad time to have this ability handy. You will be using it all game, though during end-game it can be a bit too weak.

Masteries Recommendations:
Offense 9/ Utility 21

Offense Masteries
Archmage's Savvy 3/3 .60AP/Lvl
Plentiful Bounty 1/1 Improved Smite
Sorcery 4/4 3% Cooldown Reduction
Archaic Knowledge 1/1 15% Magic Penetration

Utility Masteries
Perseverance 3/3 3% more Heath and Mana
Good Hands 3/3 10% Reduced Death Time
Expanded Mind 4/4 5% more Mana
Meditation 3/3 Mana Regeneration 1.00
Quickness 3/3 3% Faster Movement
Intelligence 3/3 6% Cooldown Reduction
Blink of an Eye 1/1 Improved Flash
Presence of a Master 1/1

This mastery build is flexible. I prefer to gain the 9% reduced cooldown and the addition mana and mana reg never hurts. Focus on mana and cooldowns.

If you follow my suggestions of having Smite and Flash, then the masteries that improve these two skills are immensely helpful. 

Runes Build:

Focus more on Mana/ Mana Regeneration/ Ability Points. Don't worry about cooldowns, because we will meet the 40% hard cap on cooldown reduction thanks to masteries and items. 

Attack Speed and Attack Power runes are not necessary useless, but they should take backseat to the previous mentioned runes.

Item Build:
I know. I know. This is the part you have really been looking forward to. I know I've been looking forward to it as well. 

Here is my recommended final item list:
Philosopher's Stone
Fiendish Codex
Frozen Heart
Sorceror's Shoes
???? (This is your choice. You might want to go for more defense to increase life longevity, or go for more ability power to raise your killing capabilities.)

You have two options. Getting the Philosopher's Stone first, or getting the Fiendish Codex first. I recommend the latter. The Fiendish Codex gives you +30 AP, +7 mana regeneration and a nice 10% cooldown reduction. That cooldown reduction is the key to getting it first. 

I recommend getting the Meki Pendant as your first item, this leads to the Fiendish Codex.

After you have one of the two items, go after your Sorceror's Shoes. The movement increase is great for chasing and fleeing, plus the +33 AP adds up to your damage. 

Next, grab the second item you were missing. If you chose the Fiendish Codex, then get the Philosopher's Stone, or vice versa. 

After those three items are set, then get the Glacial Shroud. This wonderful item grants +500 mana and +40 armor, and finishes your cap to +40% cooldown reduction. This +40% reduction takes your Timebomb from 10 secs to 6 secs, which is very useful!

Finish getting the Frozen Heart.

After getting all four items, you should be set. Feel free to gain the final item like a suggested before. Just remember that additional cooldown reduction isn't recommended since you hit the cap. 

Conclusion:

I cannot stress this enough. Zilean is not a killing machine like Evelyn or Warwick. Zilean is a wait and boom support character. Yes, you will get kills. Yes, you will get assists. Just know that Zilean is best played when you aren't selfish. Work as a team. 

I have tested this build in many games, and have been very successful. Remember this is all based on my own experiences, if you have suggestions I will be open to modify this guide. I could be wrong about numbers....it's hard to write everything down while you are in the middle of a game. Enjoy!