Zac suggested update

I play a lot of tanky engagers and I'll tell you why Zac is one of my least favorites and it's actually not about his ability effects, those are mostly fine. Though I do think his alt could use a minor damage buff.

The main problem is how prohibitive his ability costs are. Late game once you have enough mana, mana costs are basically a non factor for mana based tanks. For Zac however you are blowing through 4% of your health (which is a lot for a tank, with 4k health that's 160 health per cast) every ability you cast at full/high health, and you'll be spamming your W. You'll easily blow through a quarter of your health in the early stage of the team fight JUST TO CAST STUFF. It also just doesn't FEEL good blowing through that much health every time you cast something. Sure, you can get it back by picking up blobs, but that's a BIG IF.

If you die before you have a chance to you were just helping them kill you, if you get them you'll mostly be getting back the damage you did to yourself and often blobs are in places that will force you to take damage to get to and if you're already low from the engage. Zac isn't naturally any more tanky than other tanks so by bleeding away his own health during the engage he essentially makes himself more glassy and prone to getting bursted down before he has a chance to retrieve blobs and that's just counter intuitive to being an engage tank. Your kit should make you harder to kill, not easier.

Health costs on abilities feel MUCH better on higher damage champions like vlad and mord because your goal is not to just run in and aggro their entire team's focus, plus you build spell vamp so you get health back simultaneously as you lose it.

*The changes I would make to him are simple, abilities cost 2% of his health and blobs return 2%. Same mechanics, same idea, but making the upfront cost of casting his abilities less painful and his survival less reliant on collecting blobs without making either irrelevant. I'd totally play him then. *