[Bug] Prisoner Boss Regenerates to Full Life When Companions Are Active

How is this still a problem even after all the time Act 4 as been out?

I can nuke him pretty easy but once it becomes a race to see if he dies versus my mana pool then he'll win every time through attrition.

No matter how fast I am on the draw with the ballista, it's never quick enough.

Update: 11th time it worked.

This is continuing to happen. I have tried this boss many times now. I am using a plant companion build and an unable to kill the boss without full regeneration each time, even when i don't think a plant is in action at the time.

PLEASE ! Fix this issue! This boss encounter would be amazing if it wasn"t BUGGED !

How am I supposed to proceed?

I give up, the campaign has won. I cannot justify another moment, especially when I come up against a boss like this that doesn't work with minions and healing, that regenerates even though I used the ballista, that just one shots me even thought I'm dodging. It's a perfect culmination of a game that seems to just hate it's player base.