30 years have passed since Twilight's coronation and Discord's reformation. 31 years have gone by since Nyx's birth. The black alicorn has become a hero all this time, thank to all the friendships she has made.

A new age approaches as Nyx is told of a rumor that a spell from Equestria's founding may save a kind from eternal suffering. To do that, she must set of on a quest to understand and gain enough power to perform it.

But the kind she is hoping to save has counteracting ideas...

I recommend Reading Jussonic's stories to understand some things