Can Zac's W give Zac a added passive?
Zac's W should increase in size as he increases in size. It should deal (+[1% current health]%) more damage to those around him.
So, if Zac has a full 3,000 or even 4,000 health when using the ability, it deals 30% or even 40% more damage. So if deals 100, it now deals 130 to 140 automatically and can even increase the % health damage so if its 8% it will now deal 11% to close to 12% of the enemies health.