Takes place before the events of Dark Descent Beginning. I would strongly suggest reading it, or you may be very confused. Confuse is confuse.
Princess Luna has been corrupted by the evil of Nightmare Moon and now pursues one goal: Power.
Two years have passed since she had brutally murdered four of the six elements, but what did she do before she was confronted by Celestia, Twilight Sparkle, and Pinkie Pie?
Follow her dark story as she commits the darkest sins and does whatever it takes to have power.

The Night is Coming…