Help Finding a Star Wars Story

I would appreciate any help finding a particular Star Wars crossover story. I remember it involving Twilight finding a Holocron, and some of the Mane Six being Jedi, and that Twilight experiments with and turns to the Dark Side, but that’s about it.
Edit: I found the image used as the story’s cover art or whatever, if that helps at all.
https://www.equestriadaily.com/2015/05/drawfriend-stuff-1521-sith-lord-sparkle.html?m=1