There is a workaround, if you are stuck at the door like me.
Get a bunch of Tenebrium weapons and hack at the "your ascension is not yet complete" door.
It appears to have about 60,000 HP, but it can, eventually, be destroyed by 'brute force' (ctrl-attack)
Advice from the Codex:
Konjad said:
Equip a tenebrium weapon and beat the **** out of the doors, as I did. It takes a while (and you'd better have blacksmith skill or buy 20 weapons) but you can continue with the game afterwards.
