NO LONGER THE CANON SEQUEL. Perhaps you are looking for The Archmage's Last Bow?

It began with The Apprentice, the Student, and the Charlatan, but now the story continues, Even In Other Worlds.

Nathan Samuel is a normal guy. Decent grades in college, a girlfriend, an apartment, and a stable source of income. That much he thinks he's sure of. One fateful day, however, the spellwork of a curse surrounding everyone he knows suddenly drops from around him, and he is able to remember who he is: Nova Shine, the Night Master of Princess Luna.

Meanwhile, a coalition of villains to Equestria has been assembled to keep things in check. Queen Chrysalis, whose job it is to use her changeling forces to prevent any kind of organized uprising; Sombra, who was the one who cast the memory curse in the first place, is to keep it in check; Discord, who is doing little more than standing for back-up; and Nightmare Moon, watching the Elements personally and reporting back to their mysterious "benefactor."

Following a conversation with Princess Celestia, Nova now knows what he needs to do to return to Equestria. The Elements of Harmony were restored to the Tree of Harmony, but the spirits of the Elements live on in their Bearers. With all six of them unable to remember who they are, and worse, with all six hating each other, Nova Shine now has to work to restore the Elements, and in the process try to make his fiancée fall in love with him again, to return all of them to their home.

NOTE: Gore is rather light; tag is included for safety.