Chaos is not the opposite of Harmony but apart of it. Both chaos and order together create a balance known as Harmony. Without one you cannot have have the other and without either there is nothing.
Twilight and her mother, Luna, return from the moon a year early. Things are great for the mother and daughter duo... at first, but something amiss. What could it be?
After the second invasion of the changelings, the nobility of Canterlot are in an uproar. In a desperate attempt to keep the peace Twilight has to make a decision, on which depends the fate of Equestria.