Ponies were slaughtered. The Princesses were taken by surprise, attacked far sooner then they had anticipated, and nearly overrun by a second Changeling invasion. This time, however, the Changelings were not so easily defeated, and had slowly been gaining ground, thanks to their hordes of spies and assassins. Now, as Luna puts her newest recruit to use, the Mane Six must watch as their favorite dragon leaves behind his baby image and becomes a dog of war.