Everything in this guide is only for jungle Zac...I can't imagine him taking any other lane. There are two ways to build him, ap or tanky, both builds can be found in the first set and the runes and spell order are the same, only only difference with the second set is the ap masteries.

Of course, Zac needs a sustain item, and that could either Spectral Wraith or Spirit Visage, if you get Spirit Visage, you need Ancient Golem. Your core items are Sunfire and Liandry's, Sunfire because you can use the health, and since you stick to your target, it's nice to deal the frequent damage, then it works with your passive. You need Liandry's becuase think about it, you deal frequent aoe damage with slows/knock, so you proc it easily, and on top of that, the double damage, so whether you're AP or tanky, you can still use it well. If you're going AP, you need another AP item instead of Spirit Visage, so Abyssal is perfect, it works with your sunfire. Then you could finish with an AP item, or more health for your passive and be a meatshield, notice this build doesn't have any tenacity, so it's useless to get the mastery.

You'll want w first to take blue, it has the lowest cs and does percentage, but because it has a caps, it's not that good for clearing, so get w first, but max out q first, it also has cc. The rest is pretty obvious.