Doom and Gloom while things go Boom in . . . Equestria?

Our favorite boy genius builds a time machine in order to visit the past and disprove the existence of Nightmare Moon. Predictably, he bit off more than he could chew.

Trixie finds Nightmare Moon's discarded war helm, and makes the mistake of putting it on. Now Trixie is sharing her head with the dark alicorn's mind. However everything is not as Trixie expected when she discovers a few of Nightmare Moon&a