Very minor spoilers ahead.
I won’t mention where, but there is a Primal Shambling Mound that appears to be unkillable. He does the troll thing where he falls over and takes tons of damage but keeps regenerating. I’ve tried Adamantine weapons, Cold Iron weapons, all energy types, up to +4 weapons. He just won’t die. I read on the Steam forums that Inflict Wounds might kill him, but of course I don’t have one - and now I can’t leave because I’m stuck in combat even though he is way, way far away from me.
Has anyone been able to kill this guy?