I dreamt that Xander was working for the First during season 7 and secretly killing potentials all along. Kinda similar how folks had mentioned that Xander or Giles might have died and been villains working for the first, but in my dream the First convinced him it would give him power etc., and he cracked.

Then Buffy, a handful of trusted potentials and Xander (as her most trusted ally) went to the school to perform a ritual that would locate any existing potentials. Once cast, it was actually a ritual to see the last moments of recently passed potentials who confirmed Xander as their killer and showed how he gained their trust. Buffy had begun to suspect for some time and needed a way to know for sure. Giles, Willow, and Spike then came to take the potentials somewhere safe, and Xander gets kicked out.

Sorry, I’m trying to type this all before I start forgetting the details. There were really creepy scenes of Xander luring the girls down school hallways and shooting them or tricking them into killing each other.