Zac Combos
These are some Zac combos I came up with:
Stretchier Strike: In the middle of the Q animation, you can flash in a different direction, changing how they get pulled together.
Pancake Jump: After you use E, you can use R before you pop out of your "Puddle" of goo. This will give you more time to charge up R, due to them being cc'd.
Exploding Arm: If you use W in the middle of the q animation, you will deal more damage overall.
Teleporting goo: If you Flash before the R animation is complete, Zac will land in a different location than the people in the goo. This is useful for setup for your e and landing a quick Q.
Exploding Leap: When you are in the puddle of goo after your E, you can use W to deal more damage without them noticing. If you get all of your piles of goo, you can use w again.
Gooey Strike: This is sort of a weird one, since you need a Yasuo to pull it off. First, you Pancake jump, then, when you are almost done the R, get your Yasuo to use his R. This will lead into a long chain of cc.
If you find any other combos, feel free to post them down below.