Back in the dungeon, Douglas attempts to continue his spell, confident that he has total control over Sam. He draws symbols on Sam's body with Sam's own blood and mumbles a lot. It quickly becomes clear that Sam has to do something fast—or die.
He starts by deciding to stop pretending he's still tied up and punch Douglas in the face, grabbing for his knife. Then he stabs Douglas in the back, twists the knife, and kills him. Douglas totally just got served.
While Sam's stabbing Douglas to death, he notices that across the room, Bridin has killed Michael and is obviously filled with conflicting emotion; dude might be a certifiable jerk, but he was still once a member of her pack.
At this climactic moment, having defeated Douglas and experienced the full extent of his necromancing powers, all Sam can do is scream. Bridin notices this and gently tells him to send the dead back to the grave. He does, and feels the overwhelming sense of his power die down.