The Luna Challenge this time is… Nightmare Rarity!
When the Nightmare Forces needed another vessel, they sought out Rarity, feeding off her insecurity and fear of being unwanted, corrupting her into the new queen of darkness. It tooked the combined love of Twilight and her friends, and the combined might and cameos of Ponyville to defeat her.
You have 30 minutes to draw, followed by 15 minutes to submit!
Source for final image https://ulyssesgrant.deviantart.com/art/More-Nightmare-Rarity-372321410