Avatar of Tyranny glitch

[Romnia]

So you know how Gortash gets his daddy's boons when you fight him, including most annoyingly 150 temp hp? Yea so I'm having trouble with a glitch where he is endlessly recasting that supreme goon form EVERY TIME he's hit. I'd have to damage this homeless Sasuke looking end boss for 150+ dmg in one roll which even with a classic gloom stalker/rogue build on Astarion feels unreachable.
I'm in a hard pickle rn, playing with a single modded save. If you have any creative solutions for how to kill the guy please do share.

I did everything else in act 3 already and I dread having to put the campaign down like a dying dog over this.

[belgix]

It's a well known bug and Larian is aware of it. There are multiple workarounds to win this battle from reloading the game, flee the battle (and the castle) and get back or lure him outside and make him have an accidental (and fatal) fall.

[Thrones]

I lost it when OP said "homeless Sasuke looking end boss." Although he is right the resemblance is uncanny.