On the eve after a great storm decimated Ponyville a horde of ancient monsters is unleashed by the CMC. Now they have to work together to reseal the horde.
Cadance feels that Shining Armor isn't understanding her feelings and needs as a mare, so she decides to teach her husband a lesson the hard way. By letting Shining experience them all first hand.
An Alternate Universe were Discord revived himself a thousand years before the Mane 6 were born and battled Celestia to a draw. Story is a sort of crossover of the Slayers Anime with the MLP FIM cast playing the main roles.