User blog comment:IamJakuhoRaikoben/Chapter 384: Attack of the Stars, Review./@comment-24066070-20140516095412

If Ultear is still alive, she might be able to restore the key to the state it was before it was broken.

Would also be cool if Marde somehow managed to harvest enough "curse power" from his confrontation with the SK to revive E.N.D.

Or to add another ridiculous E.N.D theory to the long list: The Spirit King is/was E.N.D.