My Little Pony: Friendship is Magic - Sweetie Belle becomes the marshmallow

Luna visits Scootaloo, defeats nightmares.

Luna visits Sweetie Belle, scares the piss out of her with high-octane nightmare fuel.

"No! I must kill the Rarity," Sweetie shouted.
The moon princess said, " No, Sweetie. You are the Rarity."
And then Sweetie was a marshmallow.