What was the magic that cursed Stygian and Luna?

[FlareGun45 2,221]

I'm assuming they were both cursed by the same magic. I'd like to one day know about the origin of that dark magic, where they found it, and what was the original plan they wanted to use that magic for before it consumed them?

[Toastypk 920]

There was definitely parallels between what happened to the two of them, though I don't know if they were the same or not. It's easy to think so though.

Nightmare Moon was powered by some force from the moon, which was expanded on in the comics, but it seemed to spark from Luna's jealousy. In the comics, the same forces that gave rise to her found Rarity and used HER deeply hidden inadequecies to become Nightmare Rarity.

The Pony of Shadows was definitely some darkness entity that needed Stygian to accept it to become what it/they were, at his lowest point. I've had curiosity to know more about that, and the Well of Shade, though it's probably just going to be a creepy unexplained thing.