Well if this picture doesn´t have a"story" behind I will give it one: the vortex is the result of the manifestation in the mortal plane of Daybreaker after to achieve to escape from the realm of the dreams becoming a real creature in the proccess (with her own body and soul). And Celestia is watching the scene disgusting and worried knowing that the mad mare is going to become a disaster of epic proportions for Equestria and the world...