Which is exactly why I want the plot holes and hints to be addressed. If avernus is our only choice I don't think it's unresonable to know why. There are enough hints to belive something can be done, not to mention she does nothing in act 3. We don't even get to try and fail, which just can't be intentional
exactly, we don't try to search the solution in act 3, because we're not allowed to by the game.
If we completely forget about ressurections, divines and these "unrealistic" possibilities, there are at least 4 very real. But we're not able to at least talk to them, why they are not able to help. Dammon, Raphael, Mizora and Gondians. All of these acts in final act as Karlach is not staying next to Tav, no possibilities to talk with them about the issue. I think everybody who finished the campaing with Karlach in party was suprised at the end in a way "Hey, did I miss something during my gameplay? Did I something wrong in act3?"
And yet, you all seem to have missed what Karlach wanted herself.... She wanted to go out on her own terms.