"In ages past, there is a legend that is mentioned in lost lore that a mare once stumbled upon a very dangerous magic and by awakening it, she became the new host of that magic. This trapped her in a being eternally young, to posses unfathomable magic, and be controlled to do as this magic said. This magic changed her in ways that made even the most powerful users of magic worry about her capabilities. It is said that one of Star Swirl's decedents faced this mistress of catastrophe and found that she was unstoppable. He then chose to seal her and the magic away, so it never threatens Equestria again. This mare's name was Misery." - Lost Tomes of the Ancients It is a beautiful night. The stars and moon being formed from Luna's magic splendor. Though Luna this night felt a unease. Something didn't feel right in the air. The magic that blew in the four winds was growing darker. Luna couldn't put a hoof on it, but she could tell something was wrong. She would wait to morning and ask her sister about this. Maybe there is something that many returning from age's past. None could know the danger that befalls them this coming day. The darkness that will sheath over the whole land. It begins under the stars of night. Who can stop it? Can anypony stop it? Only time will tell.
Hmm... interesting idea. I do have an adventure and/or action-oriented MLP: FiM OC... Color me interested.