Rainbow Dash, Applejack, Pinkie Pie, Fluttershy and Rarity, all went to the same school at some point in time. Sadly their beloved teacher Cheerilee died there in a way they can't remember. Now -years passed the events- that very same teacher wants revenge. A revenge that can only be achieved by them bleeding to their death while screaming in agony.

Revenge on the five that ruined and eventually costed her, her life. But is everything as it seems to be? Or is this all, one big nightmare in and of itself? Frightened for their lives, the are willing to do everything to keep themselves alive and away from the killer. A killer who takes them in their very dreams.

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A story because I was bored alright, picture is a little unrelated for I couldn't really find a good one for it.
Yes, this can be considered a crossover, or at least Ponyfied version of 'A Nightmare on Elms street' and I agree, but given how I personally dislike it to make a character come from one universe in the other either staying normal or ponyfied, I went with for me the most logical thing.

Freddy Krueger, ironically, has a horrible nightmare involving a particular pink pony as he tries to get some sleep.
Hilarity ensues.

On a dark night filled with even darker magics, an insane cult attempts to give Nightmare Moon a body and life of her own, utterly separate from Princess Luna. But, when the spell is interrupted by Celestia, something unexpected is created.

Now, a little black alicorn filly named Nyx finds herself living under the care of Twilight Sparkle, only to be haunted by memories and emotions from her past. Is she Nightmare Moon reborn or is she simply a doppelganger with a soul and mind of her own? Can Twilight Sparkle protect Nyx from those who refuse to see past her dragon eyes and black coat?

Or, will Nyx be forced to inherit the sins that may not even be hers and become the greatest evil Equestria has ever known?