Last year on URF, Zac featured what may have been a bug (although it wasn't fixed for the duration of the event, it wasn't present this year) where he would revive after 8 seconds OR being reduced to a single blobbie, which made thematic sense since how do you "pull yourself together" when there's only one left?
Now, the duration change is intriguing - but I'm not sure it's fair for his enemies to expect them to deal 48% of Zac's maximum health over 4 seconds, especially on a late-game health tank that they've already probably spent 20 seconds killing the first time. If you want him to get up earlier and continue being useful lategame, why not utilize the URF behavior? This means his enemies still have 8 seconds to try and kill him, but unless they have AOE he's gonna get up pretty much regardless.
I'm going to assume this was never implemented for a reason, but I was just curious because if it was a bug maybe the potential behind it was maybe overlooked.