Zilean is one of the first champions that i ever purchased, and the only reason i did was because i had never seen anyone play him before (mind you i was still a noob back than but even now, i hardly see any zileans). what first turned me onto him was his bombs, at first my games consisted of smashing q a hundred times but soon evovlved into smashing a bunch of different keys a hundred times. this guide for zilean is only how i chose to play him and im certain their is a large amount of room for improvment.

the runes that i use for zil are rather self explanitory. 1.) mark of insight for magic pen, zileans bombs are basically useless without some magic pen, though this goes more most mage charecters. 2.) glyph of intelect for flat mana boost, it allows you to stay in lane longer without OOM. especially early game when his bombs can make him mana hungry. 3.) seal of replenishment for flat mana regen, also self explanitory. 4.) quint. of insight for more mana pen. (always a good thing)

the first person i showed my masterys found it strange that i even bothered with the extra gold. so to elaborate as to why i chose that, the extra gold is especially useful... all the time. aside from that, stick with exp boost and cooldown in the utlitys, and get the extra magic pen, as well as the ap and CDR boost from the offense tree.

I cannot stress enough that CDR is the best way to go for zilean, not only does it allow him to spam his q and e alot more, but it also helps with his ult which is the main portion of his support role ( you know that whole revive thing and such). aslo the first item you should always build is rod of ages, along with the ionian boots. boots for cooldown, rod of ages to make you ALOT less squishy and provide a sizable ap boost as well. next up is the evil tome, affordable extra CDR, AP, and mana regen. the next two parts of the build are not vital for zilean and can be switched out easily for more situational items, these two however are the ones i most often find myself using. finally rabadons deathcap which is essential for its huge ap boost that really keeps zilean in the game.

FOCUS ON HIS BOMBS! this is his main source of damage. the 3 first abilitys you get should always be bomb, rewind, bomb. double bombing can easily take out huge amounts of damage and make zilean a formidable foe. his speed boost does not need to be focused until the very end, however if you find yousefl using it to save allies or get kills by slowing enemys than by all means put some points into it earlier. it should go without saying that his ult should be leveled up whenever possible.

plain and simple
clarvoyance: extra mana when you need it. especilay usefull early game when double bombing drains away most of your mana
ignite: useful spell no matter who you play, helps to pick up the kills and reduces enemy heals. whats not to like?

finally i get to explain hwo zil should be played. ill do this by game phases
early game:
zilean is a phenominal harasser, no matter where you go (even mid is simple due to the bombs long cast range) place a bomb and back up. repeat. repeat. repeat. in no time at all the enemys health is wittled down, allowing you to either bully the lane, pick up the kill, or force them to go b and you can dominate the lane. also double bomb whenever you can (i.e place bomb, use rewind, place another bomb) until you get atleast the catalyst protector be careful because zilean, like most supports, is very squishy and you can easily be picked off if you get careless.

mid game:
this is when zilean really picks up and deals out tons of damage. its interesting to note that many players underestimate zilean because so few players use him. this allows you to remain un-focused and dish out punishement. by now youve leveled up your bombs a good deal and thier taking out squishy enemys with ease. often times a player will feel like the can get a few more hits off before escaping. this isnt the case with zilean, many time sother playres wont notice the bomb floating over their head till its to late and their narrow escpae just means zilena gets the kill... again. another wonderful thing about zileans bombs is that it makes him a fantastic tower diver, if a wounded enemy is tower hugging, run in behind a minion wave, place a bomb and get out of turret range before it blow, you pick up the kill and dont even take any turret damage. if you find yourself being chased alot always use your e to slow an enemy instead of speedin yourself up if you can. it gives your more time to react. also ALWAYS be ready to use your ult on a teamate or yourself, preventing ally deaths is what supports are about to be ready to... well.... support. also in team fights, if you place a bunch of bombs, due to the area affect of the bombs, i fyou dont get kills you will be garunteed asissts becuase of the bombs.

late game:
unfortunatly here is where zilean drops off as a damage dealers and picks up on the support role, late game you wil find youself using your ult and e more often than before. since you have so much CDR from your w and items, your ult should be ready every 25 -30 seconds at lvl 18 if you spam W. which means you can prevent a huge amount of deaths and in a lot of cases allow your team to come out on top in team figts. zilean ult is great becuase it allows 7 seconds after casting for the recipeant to die and than be revived. i cant even begin to tell you how many times i would ult one of our main dps'rs (ie tryn, cait, noc, yi, etc.) the enemy would rush past his "dead" body to chase me and he would suddenly spring up again taking the enemy team by suprise and come out with anywhere from a double to a quadra kill.

story time:
i was playing a 3v3 with 2 friends. it was zilean (me), tryn, and mundo. mundo went afk before the game started so it was a 2v3 against us. late game it became a repetative thing of tryn rushing in, taking down one enemy, or atleast almost killing them, endless rage, he got a guardiaj angle, would die, get back up, i would ult him, he would die again, and just get back up. it was as if he just couldnt die and it was awsome. we destroyed the other team who consisted of shyv, blitz,and olaf.

Pros:
awsome support late game.
huge damage dealer early, mid game
great harrass
natural escape
bombs
lots of spamming

cons:
mana hungy early game
squishy
damage drops off late game