When a mysterious cult of ponies kidnaps Button Mash and takes him to a mysterious island to be sacrificed, the Mane Six, along with four stowaways, set out to save him and find out why he of all ponies was targeted. However, the reasons behind this may bigger, stranger, and more malicious than anything the ponies could ever imagine. The Dark Entity is asserting its dominance over their world once again.
(The title is clearly a reference to "Hades Persistence," the title of an episode to Beyblade Metal Fury.)

Scootaloo is missing. Vanished. Rainbow Dash is extremely worried about her little sister, and things soon grow form bad to worse when Goldie Delicious arrives in Ponyville to inform the ponies that Scootaloo has been taken by a creature known as Slendermane. Desperately wanting to save her sister, Rainbow Dash makes it her mission to confront Slendermane and get Scootaloo back. But could it be that it's already too late to save her?
Inspiration comes from "Slender: The Arrival"

"Wahoo! My prayers have been answered!"

Rainbow Dash always prayed whenever she could, but hardly considered herself a user of passionate prayer. The only thing Dash ever showed humility in was her Faith. However, being trapped in Ghastly Gorge during her own pet race put her in a really dark place. Filled with fear and trembling, Dash knew she had to reach deep within her and call out to her Heavenly Father in earnest prayer. And to her amazement, God sent a miracle.
Contains Christian themes.

With Daring Do as his prisoner, Ahuizotl discovers the temple where Scorpan sealed away the Rainbow of Darkness. The Mane Six, joined by Celestia and Luna, quickly go to prevent such an evil force from being unleashed. However, it turns out their attempts to reseal the Rainbow of Darkness cause some unforeseen consequences. Only the Rainbow of Light can set things right, but where could it be? It turns out that its closer than they think.
(Takes place after Season 4. Elements of G1 are used. NOT a character turns evil story.)