What started as a relatively normal day in Ponyville quickly takes a strange turn. Rainbow Dash learns that Rarity and Fluttershy have an exciting secret hobby, an unidentified object crashes into Sweet Apple Acres, and a mysterious unicorn appears to Twilight and Pinkie speaking of a distant kingdom and a diabolical plan. If somepony only understands violence, is the power of friendship enough to stop him?

Source for the cover art - http://sanr4.deviantart.com/#/d4o2hk5

(I personally don't consider this a crossover, I call it a spiritual adaptation, but most people would say its the same thing)