In theory, Larian possibly could have had a sequence where Damian show up to try and stop you, but the objective would be to run away and enter the portal. Damian wouldn't be able to follow you without the protective amulet.
The problem with that idea is that NOT fighting the big boss-like enemy is counter-intuitive, even with voice-overs from "Talana" telling you seriously run, and having Damian be invincible and able to do huge damage to you. I suppose they wouldn't want the player to blow all their potions on a fight they can't win.
