Elements of Harmony

six supernatural artifacts which are arguably the most powerful force in Equestria, though the extent and nature of their power are largely unspecified.

The Tree of Harmony presented The Harmony Box as a result of being confronted by all of the bearers of Elements of Harmony, and the controllers of the sun and moon.

Elements of Harmony are advanced technology created by a civilization that inhabited the world before the Ponies.

The Harmony Box contains upgraded versions of Elements of Harmony.

The Tree of Harmony and the Elements of Harmony were created by Ponies thousands of years ago.

Nightmare Moon is actually her normal form. Princess Luna is her "powered down" form due to the use of the Elements of Harmony.