Brand+Zac
honestly i love this zac ult, i don't understand who thought this Q idea was good but that ult whenever i see zac in my team i just build around him and pick brand sup instead of thresh and destroy everything in teamfight
this is going to be less effective once people learn to not group around zac ult everytime they want to kill him
don't judge a rework only by win rate, riot can easily fixe the numbers, what you need to judge is the design and this ult gives zac a niche, countering 
and becoming strong with AOE champions unike the old generic "i press E on the entire team+ult instantly to remove 40% of their hp and control them" because honestly this was like most of the tanks niche.
pluck an enemy carry from their fountain and bring it to our fountain