Celestia is not having the best of days. Luna goes evil and turns into Nightmare Moon. Nightmare goes onto making the night last forever, once that was taken care of she would go onto kill Celestia. Then it starts all over again.

This is my first try at a time loop story.
I want to thank Evilhumour for the idea of this story.

This is the best art I can find of these two.
Art is done by TysonTan