Lol yeah idiotic name.

So uhm...this actually has a little bit of canon in my story. (this is canon in a story where Mia fell in Equestria. But I have another story where he enters a pony dimension yet there is no MLP canon characters there).

Here it goes:

After a lot of Twilight's experiments about the source of Alicorn magic failed, Luna decided to close the laboratory. Little she knew that there was an ongoing spell that was time triggered, as soon as Twilight and Mia returned to cancel it, the spell triggered and the mishap happened. Now Mia is holding within himself the alicorn power of the Lunar Princess, and has to take over the role of Dreamwalker and chase off nightmares from ponies dreams!

That actually has a lot of potential and I might use it soon~
Another explanation: Mia can't control his horn to channel magic, so he received that magic staff from Twilight, which added some little bit of fashion (Thanks to Rarity incredible insistance on that it would be a fashion murder to make a magical stuff without proper magical outfit to go with it) so here we go. Mia in a Princess Luna inspired outfit together with the staff, horns and wings, and Princess Luna herself as the magical advisor on how to deal with nightmares.