My biggest joy killer in the fight was the fact that Rath and Silver were always considered part of the combat, even though they stayed at the gate to the inner room and did nothing. So I was fighting at the gate and every turn I would lose a minute just because the game would jump to the two of them doing nothing. This also meant that I spent more than 20 minutes just dashing from the gates down to Rath (excluding the fight against a few Tieflings on the way) because I was always considered in combat.
The further down I went the whole grove fight, the more bugged things became. The goblins with the explosive barrels on their back were officially part of the fight against Rath and Silver, but all they did was saying a line of "You only make it worse"/"I'll kill you" and stay right on the spot. The Goblins on the same level as Rath and Silver didn't do anything, either.
Even Rath and Silver just stood there as I kept lowering their HP.