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Disclaimer
Burst AP Zac is an off meta for-fun pick, if you are looking for a serious AP build, go semi tank with Demonic Embrace and Rylais.

Playstyle
Simply Ambush your squishy enemies with your E and instantly W, use Q+R+Smite if necessary. You can full combo any squishy when equipped with your core build as mentioned above.
Full build you One-shot squishies with E+Instant W which procs Dark Harvest.

Be carefull of Hard CC that can stop your R or displace you when Ulting, and before jumbing in, make sure that the enemy either has slow reflexes or has their mobility skills on cooldown.
Your playstyle is similar to Fiddlesticks, you hide out of vision and jump in to kill people.

1. Using Blue Smite on your target while mid-air with your E, slows them which gives you a higher chance of landing your E.
2. Don't forget to pick up your Passive Blobs to reduce W's cooldown and also heal.
3. Use your 1st Q on an easy target such as a minion or monster, or better a CC'ed champion and then attack your main target. You can also proc the 2nd part of your Q by attacking Towers, Traps, Wards and any enemy unit that can be basic attacked.
4. Farm well, last hit kills and target squishy targets, that's the best way to get gold, which means items, which translates to Damage, you also need to stack your Dark Harvest!
5. You can Q, E and then proc the 2nd part of your Q as long as you don't get out of it's range!
6. Use your Ult's knock back to place your target away from their escape route.

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