This story is a sequel to Luster Dawn: New Days of the Magic of Friendship
Follow the Endings for the Legion of Doom that you prefer. Different fates await Chrysalis, Tirek, and Cozy Glow after they have been defeated and surrounded again after being released from stone by the real Grogar. Part of the Successor Verse.
Both light and dark versions will be featured here following the ending that occurred as there two options one can follow. Reading those stories is optional but not required. I'd recommend New Days as it tells the whole story in one.
In Light: All three are redeemed and are sent to Tartarus to serve a prison sentence for a time but will be released and given a second chance after seeing the error of their ways.
In Dark: Chrysalis refuses to give into the final shot at redemption and attacks Starlight in a final act of revenge. Starlight and her family and friends fight back and kill Chyrsalis, Tirek tries to avenge his comrade in rage but is snapped by Discord into the sky where he falls to his death. That leaves Cozy Glow who is captured and sent to Tartarus for life. But will she spend her life there? Or escape and seek revenge?