A few more whacks from the troll hammer knocks Glory completely into submission, and she changes back to Ben. Giles comes over and realizing that Glory would still come after Buffy despite any agreement with Ben, he blocks Ben's nose and mouth so that he can't breathe, effectively smothering Ben and Glory from this plane of existence. Meanwhile, Doc's already started the ceremony. He makes a pair of shallow cuts in Dawn's stomach, allowing Dawn's blood to begin to flow. Buffy hits the top of the tower, pushes Doc off, and grabs Dawn, but the light from the portal opening stops them both from leaving.
Horrible things begin to happen.
Energy bolts strike all over the place, including over Anya who's buried under a pile of debris from the construction site. Others hit buildings and turn them into hellish buildings. Still others cause earthquakes, and fissures appear in the ground. It's looking pretty grim for the world. It's at this point that Buffy finally realizes what has to happen.