At this point, the player learns that only a Grey Warden can slay the Archdemon because of the Taint present in a Grey Warden's body. Killing the archdemon releases the demonic essence within it, which is automatically drawn to the Taint in the Grey Warden who slew it, and effectively kills him or her as well; if anyone other than a Warden slays it, the Archdemon's essence survives and finds a new host in the nearest Darkspawn, making the monster effectively immortal. On the night before the final battle, Morrigan offers the player's Warden a way to slay the Archdemon without sacrificing anyone: Morrigan believes that if the player succeeds in conceiving a child with her, that the child would also carry the Taint. Once the Archdemon dies, its demonic essence would be drawn away from any Grey Warden to safely merge with the unborn child instead. The resulting child would be born a demigod, which she plans to raise on her own. Morrigan admits that this was her true motive for joining the player's campaign all along. The player can accept Morrigan's offer, convince Alistair or Loghain to take part instead, or refuse the witch's proposal, causing her to leave the party. If the Warden is female, she can only refuse Morrigan or convince Loghain or Alistair to do it.
The next day, the player and the newly assembled army of Ferelden fight their way through the city of Denerim, which is now overrun by the darkspawn. After fighting their way through the darkspawn horde, and an epic final battle against the archdemon atop Denerim's highest tower, the player is given the chance to deliver the killing blow or to let Alistair/Loghain do it. Either way, the archdemon is killed and the rest of the darkspawn army retreats from Denerim, marking the end of the fifth Blight. Unless the player chose to sleep with Morrigan, whoever slew the Archdemon also perishes. Should the player choose the ritual, the option to allow Alistair/Loghain the final blow is skipped: the cutscene showing the Warden slaying it plays automatically.