In this story Miss Cherilee teaches the students about an ancient entity of darkness known as "Darkwing, The Angel Of Darkness".
and that it had been imprisoned in anything or anyone.
So when Diamond Tiara suddenly notices a dark power emanating from her flank and crown, she and Silver Spoon are chosen by "The Angel Of Darkness" To destroy The Spirits Of Harmony.
But now Darkwing has used the Stone Of Age And Youth to play The Song Of Youth across all of Equestria, The Mane 6 are the only mares to stop him, What's more is that Darkwing has engaged his final form and is now ready to end Equestria with one fell swoop, Will Twilight and Friends be able to win the day once more?
This was my first fanfic, so excuse me if it's a little rushed or has some plotholes in it. I was just a beginner at the time.