"Nebula!" Celestia and Luna burst into the library, confident and determined looks upon their faces, much to Nebula's amusment.
"Ah, Princesses. Lovely to see you again. It's been so long, hasn't it, Luna? Perhaps we should chat a little, get caugh u-"
"We have nothing to say to you, Nebula. How dare you think you can simply waltz in here, destroying and breaking whomever you wish? You only bring pain with you, Nebula. No- you do not cause it. You crave it, do you not? You simply love the pain of others." The regal Moon Princess paused for a moment. "Do not think for a second that We fear you. You will fall, keep that in mind. And do not even think about coming back. This is the last time, Nebula. The last time somepony gets hurt because of you." Her Royal Canterlot Voice echoed loudly through the library.
Nebula's expression was uncertain for a moment, as if he was worried, but it was swiftly replaced by a smirk and a chuckle.
"Two little ponies against a powerful being twice as large as you, with twice as much magic. How, exactly, are you going to defeat me?"
Celestia stepped forwards. "Because this time, we don't come alone."
At that moment, seven ponies strode into the room, each with a crown upon their head. Without a word, they formed a circle and the tallest of them, a unicorn, was charging his horn.
"What the..." Nebula said, staring at the sight of it. "No." He whispered as the seven ponies lifted into the air, a rainbow that he knew all too well emerging from the center of them and making a path straight for him. "NO!" The light, the vicious light, everywhere! Blocking out his senses as darkness began obscuring his vision. The last thing he saw before his vision faded was Luna, standing over him.
"Sleep tight," she whispered, Nebula finally falling into a deep sleep.
"You have done well, today, Elements," Celestia addressed them, nodding to each one in turn.
"Thank you, but we must leave now. This is not our time in history." Starswirl glanced back at the other elements. "And.. I do not think I am worthy of any element I bear." At this, a look of surprise spread across the face of Celestia.
"But you created the elements, how can you say that?"
Starswirl laughed wryly.
"I understand Harmony quite well, but friendship? Friendship is simply a mystery to me." He took his crown off and destroyed it in a blast of magic. "My element is not needed. Farewell, princesses of Equestria." In another flash of magic, he and the other elements disappeared.
.