you are a Guardian you protect the ponies who bear the elements of harmony and fight in wars that happen between the ponies and the other races. The guardians were thought to be all gone you are from the family that is the last of the Guardians you accept Princess Celestia's request to help Equestria in it's time of need. The ponies are headed to war the Princesses don't want to admit it, but they know it's true it's time for you to fulfill your destiny.