Season 4 of My Little Pony: Friendship is Magic is an upcoming series of the TV show.
A few trailers have been released on YouTube:
The Nightmare Returns Part One and Two
After Twilight earns her wings, she is given the task to time travel to a very dangerous time - the first time Princess Luna became Nightmare Moon.
Things get more petrifying as Sunset Shimmer returns and helps Twilight complete her task. Can Nightmare Moon be proven wrong in conquering Equestria?
Firefly returns to Equestria to seek a disaster which must be erased. Can she succeed?
The ponies become superheroes to defeat a villan who seeks to destroy Equestria.