So, we killed the Owklbear and (unfortunately) put the cub out of its misery, but then, walking to the back of the cave, 2 of my characters fall to the necrotic miasma. 2 things wrong here: 1. They weren't dead or down, yet something drew them to death. 2. Again, no control of characters' locations after combat MAY have put them out? Anyway, they're dead, no Help works, no Long Rest.. Purgatory. Can't go anywhere from here except reload the last Save.

Was one of them Gale?

Sounds like you might have had Gale knocked down by something (maybe he was low health after the fight and pathed into a trap?). If Gale is knocked down and dies his body gives of a necrotic miasma that damages those around. You should get a cut scene for this partially explaining why the first time he is killed.

True, which is also a problem. I noticed the damage keeps ticking on the background while you are locked in a conversation with the....what is it? A sentient vision? I dont know but it caused me multiple character deaths already xD

Yeah that cutscene can be a Total Party Kill if you don't know it's coming

Thanks for the responses. One of the characters was Gale! Perhaps, I guess I should have named the thread "GALE..not cool!"