Nightmare Moon and her lunar knight had returned to the royal castle. Bbefore beginning their attack Nightmare Moon granted a boon to the knight, using her dark magic she had syphoned all the magic from the surrounding forest and used it to grant the knight the same everlasting life as the alicorns. If she were to rule Equestria forever she wanted a loyal soldier to serve her for just as long.
And while granting an incredible gift to the knight, without the natural magic, the forest would become wild and unmanageable in years to come, forever being known as Everfree.
Afterwards, the attack had begun. The common soldiers had fallen before the knights blades and the alicorns powerful magic. Soon they stood before the throne room where Celestia waited for them.
Celestia was staring out the far window as Nightmare Moon walked into the room. Without turning she asked in a heavy voice "Luna, why have you done this?"
Nightmare Moon's voice however dripped with anger as she said "I do this because you don't know why. You honestly never looked over your shoulder and asked yourself how I felt! Just like the sun blocks out the moon, it blinded you and everypony else to my pain. I suffered! I was sad and lonely and you never once helped! Less and less people cared about me and my night and when nopony came to the winter moon celebration what did you say? "Maybe next year Luna." Ha! We both know it would have been exactly the same."
"Luna... I'm sorry you felt that way, I truly am. But I never basked in the glory; I simply performed the duties I needed to do for the wellbeing of Equestria."
Nightmare Moon scoffed. "At the cost of your little sister."
"Luna, I-"
"Save it for somepony who cares." Nightmare Moon said. "Soon I'll be the ruler of Equestria, and I'll get the attention I deserve!"
Celestia hung her head. "So there is no reasoning with you? There is nothing I can do?"
"Nothing." Nightmare Moon replied, horn glowing.
"Then... I will do what I must to protect Equestria." Celestia said, turning to face her sister.
"Try it... Tia." Nightmare Moon said. Her horn crackling with lightning.
Celestia closed her eyes and began glowing a gentle white. Her hooves left the floor even though her wings remained closed, and all around the throne room six points of light began glowing as well, resonating with the sun princess. After a moment six shining orbs seemed to float out of them and gather around Celestia.
Nightmare Moon unleashed a bolt of lightning. It met an invisible barrier around the orbs and ricocheted off, obliterating the ceiling and sending rubble raining down.
When Celestia opened her eyes they too were glowing white. And even through this display of power tears could be seen on her face as she spoke. "Nightmare Moon, you have disrupted the natural balance. Threatened the way of life for everypony in Equestria, and perverted the suns purpose by using it as a weapon to destroy an entire city of innocent stallions, mares and fillies. I have given several chances to repent and you do not. Therefor I have no option but to use the Elements of Harmony."
The knights eyes grew wide at the mention of the ancient artifacts. Surely the elements were just an old mares tale? They couldn't be real! Nightmare Moon on the other hand seethed with anger, eyes narrowing as she screamed "Innocent? They shunned and insulted me! They're all guilty!" once again her horn ignited and she fired bolt after bolt at Celestia, with no effect other than destroying the castle around them.
Celestia emanated a pulse of rainbow energy, which seemed to capture Nightmare Moons magic and stripped it from her horn. "Nightmare Moon, I will not kill you, but your crimes will not go unpunished. You hate the day so much, and love the moonlight, therefor you shall be imprisoned on its surface for eternity."
For the first time Nigtmare Moon showed fear, unable to use magic she could only stand and watch as Celestias white glow intensified.
With a scream of rage the knight drew his blades and rushed the Princess, only to run nose first into an unseen barrier. Unable to do anything, he turned and watched as his queen became enveloped in a white glow. The shining light became so bright that he couldn't look at it anymore and closed his eyes. After a moment there was a rush of wind and the light faded.
When he again opened his eyes he looked up to see the light fading as it grew smaller, as it soared to the moon. a moment after vanishing from sight. Within seconds the light vanished from sight, the moon releasing a flash moments later. Upon fading the knight could see Nightmare Moons' likeness upon its surface.
The knight turned to watch as the light surrounding Celestia faded, the orbs drifted away from her and landed atop the fountain, fading to stone before his eyes. With a final dimming the sixth orb left Celestia and faded from sight. She then turned to him and said "Enough tragedy has taken place today. Leave now and I'll forget you were ever involved in this."
The knight was seething with rage inside, but knew he couldn't take the sun princess. Dipping his head he turned to leave, but as he took to the air he said "No Celestia. Forgetting me would be the worst mistake you can make."
The night sky brightened as the forest faded from view behind him. Within minutes the sun began to show its brilliance over the horizon, painting everything in a golden light. To the west the knight watched as the moon carried his queen from sight.