The changelings have been brought to the brink of extinction. In a final, desperate attempt to save their race, they create new strain of changeling using the essence of Twilight Sparkle, later naming him Dusk, hoping he will be able to rebuild their species. With Equestria now headed toward an all out war with its old foe, Twilight is forced to come face to face with her inverse self and the reality that not everything can stay perfect forever.