Hey Everyone, Skellybur here and surprisingly enough, this build was short and sweet for me, but I have no idea what you're going to picture this, when you see both my mid and support Zilean Builds. And hoooooly Phreak, does he do work. (At least on support, He's having issues for mid, imo.)

Mid Zilean:
Mid Zilean is where he has the most Trouble, Even though he doesn't exactly need to worry about sightstones or Frost Queen's. What does suck for Zilean on the other hand is that it seems as if He's forced to build into Defenses while getting some AP at the same time; Making his Build some of the most undiversed in the entire game. (For Mid, at least.) On the Bright side, you can actually play this around, by playing him how you would standard in the game, expect that now you can't die by the pure items that you build onto him, and plus he will still do some AP Damage, not the biggest or the best, but it's better then staying squishy and dying all the time, which Zilean can just brush off with his ulti.
Example Build: Zhonya's Hourglass, Mercuary's Treads, Abyssal Specter, Void Staff, Luden's Echo, Guardian Angel. And for your Spells, you want to take either Heal, Teleport or Ignite, and Flash.

Support Zilean:
Support Zilean can play similar with Mid, expect less ganks and more wards, and He's known to use his spooky ghost to scan about where the enemy team is. He's viable to die up until his forth build, where he brings up his Zhonya's or GA, and making him more of a nuisance to kill. This does mean that he needs to play passively and anchor his ADC whenever possible, but as soon as he gets his Zhonya's on, sudden he doesn't need to worry as much about his death sentence. You can just use your ZH, then quickly use you're ulti, and if you have a GA, now they are wasting up to 10 seconds, which is about 7.5% ~ ish Percent to complete a full 75 second respawn at super late game. Zilean with this build is to make sure that you become annoying to take down in general, at late game. escpialy at ganks or Team ambush, but at early game he still hates that. Spells are basic as ever: Exhaust and Flash.

Exmaple Build: Sightstone, Frost Queen's Claim, Mercuary's Treads, Zhonya's Hourglass, Guardian Angel or Void Staff, Vice Versa

For the Riches: Since there really isn't any expensive skins for Zilean, the best thing that you can do is use either Old Saint Zilean or Blood Moon Zilean, which are both OP Skins.

For the Standards: Groovy Zilean. 'Nuff Said. And Occasionally Shurima Zilean, because it's kinda cool. I don't think anyone ever uses Time Machine Zilean, but it's not an disapproval skin.

Disapproval Skins: None..? Time Machine Zilean...? *shurgs*

TL;DR: Timestomp your way to Diamond, with Zilean! (Oh, and Ekko too. But I'm not there yet, am I?)

For Full Info.: If there is one thing that Zilean loves making you do is waste your time, when is allies are either respawning or pushing top or whatever. He's basically the support version of Singed at times, when you think about it, expect that he's most annoying for the 4th build, and Singed when he's at your loading screen. Jokes aside, He has to relay on his Stickies and make sure that they either poke you down and hard, or stun you, and he uses his E like a mini Exhaust or a Better version of Ghost. Oh, and did I mention that his Passive allows him to give any one of his buddies free xp? gg bot lane.

Oh! And Speaking of which! Next up is actually Singed. What a coincidence.