Hello. This is a Ziggs guide, not Zilean.
Ziggs isn't in the database so ya.
My friend who doesn't know how to build anyone unless he has a guide bought Ziggs.
So he asked me to make one, and hurr it is.
Although, it may suck.

Self explanatory, MP runes, Health per lvl runes, AP per lvl runes, and AP Quints.

More damage.
More mana.
Lower CD's.

You will want to build ROA first to benefit from its passive ASAP.

Followed by Hextech Revolver so you can buy Amplifying Tomes for some cheap AP while you're still in the laning phase.

Rabadons Deathcap next, to finally get some real damage.

Now, Will Of The Ancients. Turn an ordinary Hextech Revolver, INTO AN AWESOME BOOK WITH DOUBLE THE EFFECTS.

Void Staff, Get AP and reduce Magic Resistance at the same time. AMAZING.

AND LAST BUT NOT LEAST. Morellos Evil Tome. The Deathfire Grasp with better stats but no passive. Why not Deathfire Grasp? BECAUSE UR AN AOE MAGE. The extra AP and CDR would be much better for you to kill groups.

Ofcourse, if the extra hp from ROA isn't enough and you find yourself constantly dying like a returd, Then go buy some defense. Whatever the enemy team is consisting of mostly, buy an item to get more armor or magic resist. Such as Banshees Veil, Thornmail, FON, or if their amount of AD and AP are too balanced, get something like guardians angel where u get both MR and Armor. You can even get Warmogs if you like looking at a healthbar with lots of lines on it.
A decision, you shall make.

Obvious enough.
Max your Q first, its dependable.
Unlike E, where you have to get in real close to activate.
Or W which doesnt have as much range as Q and has a much longer CD.

Max E Second, Strong Slows are fun slows. Plus its damage is amazing when someone decides to step on almost all of those tiny bombs.

Max W Last. We do this because it is mainly a utility spell due to its long CD.
Check Bushes with it, explode it opposite to the direction you wanna go to escape, knockback your enemy a bit nearer to you or into your E.

Level you ult whenever you can. (derp.)

Flash and Ignite.
Common for mages.
Flash syncs well with your w if you fail to place it near you, just flash over it and activate, then your FREEEE (usually). Also can use it to chase your near dead enemy and use ur awesome range Q.

Ignite is to finish off escaping opponents, or to use in a 1v1 to gain a slight edge and save your lief. Also for when ur about to die and there's that ******ed 30 hp enemy trying to take the kill.

Sorry. This guide sucks, its my first.
Just helping my friend get a bit better.Rate? lol.