The witches put their plan in action before the apocalypse, making sure Mallory and Coco get a spot in the Outpost. They wipe their memories and prepare for everything to run smoothly. They then wake up from where they were buried in the ground when Mallory is ready for them. They arrive and battle Michael.
They have a few surprise guests, all of which end up dead. In fact, it becomes a bloodbath all around, with Cordelia killing herself so that Mallory is revived. Mallory goes back in time when Constance is watching over Michael.
When Michael kills the priest, Constance throws him out of her house and he gets run over by Mallory three times. Constance refuses to let him become a spirit in the Murder House.
In the present time, everything seems to be good. Mallory wonders what her changes mean for the future, with a few flashforwards offering that insight to the audience.
Emily and Timothy still end up meeting, they have a kid, and he ends up killing his babysitter. In a chilling parallel, they come home to that scene only for Mead and the other members that support Satan showing up at their doorstep.