I Will Make Them Remember

Nightmare Moon is tormented every Nightmare Night during her imprisonment on the moon, but now her powers are returning, and she intends on using them to exact her revenge.

Imprisonment on the moon.
That was the sentence charged against the weakened form of Nightmare Moon.

Years of solitude threatened her sanity, but there was hope. She could hear distant voices calling her a single night every year. Ponies finally appreciated her night!