Your right, the hard part of this build is getting warmogs on time, which is y I like to try and solo lane. I'm not sure why u had trouble harassing early game, with your quick tear and chalice u have plenty of mana, you can almost spam bombs every time ur cd is up as long as you dont use rewind much, and you level so quickly that you do some nice damage with them early game, by the time the enemy gets some mr and health you will hopefully be switching over to your tank items. Owning the lane early also helps you farm quickly. I still believe his support spells are what make zil strong late game, and that even with a decent ap build he's still a weak nuker and a squishy target.

I don't play zil much in ranked, but when I do I still use this build and I'm rank ~1500 atm if that means anything.

Played with this build or tried to accomplish the mentioned build in ranked 5v5 games with no success at all. Ok I might have won couple games against newbs but when things get tough e.g. your team is losing from the start this particulary build doesnt let you have a slight chance to make a come back.
First of all because this focuses on CDr/spam abilities gimping your AP to the ground, going up until Warmog takes way too much time cause its too expensive you need exactly 7805 not counting the extra wards or pots you might need.

Starting with meki pendant with 3 Quints of HP/regen and not flat HP puts you barely to 580hp if i recall correctly maybe even less and because of it one of the main keys of Zilean's ability, to harass early game, is if not nulified, inexistent. You will start with 1 AP at level 1 with this build so you tell me about it..

The only good thing this build excels at is at spamming your slows, bombs and to a less extend your ulti, although your bombs wont do much dmg, just for intimidation as the enemy team wont expect you to get this weird build. No offense.

You either remove tear of godess or chalice out of the build cause you are easily focused down before you even reach the first item of warmogs. I would also suggest going for defensive mastery but I wont go into much detail as really loathed this build after playing it several times. Too many flaws....and its not my job to do so ^.~

Anyways thanks for suggesting a Zilean tanky build, Im sure there will be one that will work badass as Kassadin's one but this particulary one doesnt, at least not in solo queue ranked games.

The strategy is pretty strait forward, but actually playing it is a blast. Your constantly speeding around the map saving teammates, snagging enemies, and baiting/tanking like a pro. Be sure to let me know how you do, I'd like to know if my guide is concise enough.

This is exremely unique, I almost always see zil made pure AP. The tanky idea looks like it'll work. I'll let you know what happened when I try it. There doesn't seem to be anything technical about zilean it seems insanely straightforward. Almost... boring. But tanking with him seems cool.