Fear of the moon

Seven hours later the sun has risen, but the sky appears as if something is wrong. Twilight looked outside and saw the moon right on the edge of the horizon. She was about to come to a conclusion about what was happening, right when she was about to turn around and start talking there was a burping noise and a flash of green light.

“Hey Twilight,” Spike started. “Message from the Princess.”

“Thanks spike.” She said happily as she took the scroll, when she opened it her face turned white at what she read.

“Spike come on we need to go.”

“Uh, where?”

“We need to get the others, something bad happened.”

“What happened?”

“Luna’s gone missing. She disappeared last night”

“What do we do?” Spike started panicking.

“Right now we have to get the others, princess Celestia wanted to see us all in Canterlot.” She continued as she levitated spike onto her back. After that Twilight raced out the door. An hour later on the train ride to Canterlot, the others were finally told what happened.

“So she just disappeared?” Rainbow dash asked in confusion.

‘That’s what the letter said, in fact that’s pretty much all the letter said.”

“That doesn’t make sense. Who would kidnap princess Luna?” Rarity asked.

“I don’t know, but I can already tell it has something to do with wanting to reincarnate Nightmare Moon.” Twilight started worrying .

“Well whoever they are, I hope their prepared to deal with us,” Apple Jack said with bravery.

“Yeah, they’ll be no match for the six of us!” Rainbow dash cheered. When they arrived at Canterlot the train stopped in front of the main gate.

“Why are we stopping?” Apple jack asked.

“You six need to get off here, Princess’s order,” The conductor said as he entered the car

“But we aren’t even in the city!” Rainbow complained.

“Sorry, but princess’s Celestia requested that you six depart here.” They all started groaning as the picked up their stuff and started getting off the train, and as they walked out the door they saw Celestia  standing outside the car.

“Princess?” Twilight asked in confusion.

“Twilight, thank you for coming in this urgent matter.”

“What’s going on?”

“Princes Luna was kidnapped during the middle of the night, we were doing an investigation of the castle but-“

“But luckily for all of you I was out on a midnight stroll through the city when I saw a strange pony dragging an unconscious princess through the streets” Discord interrupted.

“And how do we know you didn’t do it?!” Rainbow demanded as she flew out the door. She was right up against his face.

“What, who me? Why I’d never do something like that-“

“Yet you’d turn Pony-Ville into chaos city, and manage to kidnap both princess without trying.” A familiar voce interrupted. They all turned around and saw Shining Armor and Cadence.

“Shining Armor, Cadence!” Twilight cheered as she ran up and hugged them.

“It’s nice to see you to Twily.” He sighed as both him and Cadence smiled.

“So Discord, you were saying something about a strange mare?”

“Well I WAS, until a RUDE pony interrupted me. Now as I was saying I saw the mare yadda, yadda, yadda, she left the city and I followed her to the Ever Free forest.”

“Why would they take her there?” Cadence asked.

“I wish I knew, but whatever their doing we have to stop them.” Celestia interrupted. She raised her horn and in a flash of light she teleported all of them into the main chamber of the ruined castle.

“Why are we here?” Twilight asked.

“The question dear Twilight, is why wouldn’t we be here? I saw that weirdo drag her here.”

“Sister are you here?! Can you hear me?!”

“Sister!” Luna called from the upper level. They all raised up the stairs and saw Luna lying in the middle of a white chalk circle.

“Luna!” Celestia yelled as she ran over to her. “What happened?!”

“It is a long story, but right now all you need to know is that-“

“Is that I’m trying to bring back the greatest mare who ever lived.”  A mysterious voice said from a distance. They looked at the altar and saw Agony.

“Who are you?!” Celestia demanded.

“Here we go again. My name is Agony. The Black thorn of Equestria, the sun’s pain, and the shadow of the moon.”

“Why do you want my sister?!”

“I’m trying to bring back a legend.”

“What legend do you speak of?”

“The legend of nightmare Moon.”

“Why  would you  bring her back, she’s a monster!” Twilight yelled.

“To you maybe! To me, she was a hero, she was my idle. But you took her from me. You turned her back into, that.” She pointed at Luna. “Because of you, Nightmare Moon is no more, and because of that, I was trapped in time, for a thousand years!”

“Please, I’m sorry for trapping you like that but, you cannot bring her back into this world!”

“To bad princess,” Agony paused as she walked off the alter. “See that white ring beneath you? That is known as arcane, the most powerful of magic. I’ve been studying these types of spells for years now, and if finally managed to master them. Once that last line is connected, Nightmare Moon will be reborn, and Luna will cease to exist.”

“What do you mean?” Twilight started to panic.

“Once the circle is complete, Luna will be treated as a sacrifice, her soul will be removed from her current body, and placed into a new one. And as a result, that body will be destroyed-“

“You can’t do that!” Celestia interrupted.

“To bad princess! It will be done, and you will not stop me!” She shot a beam of magic at the ceiling again and same as last time a large piece of stone fell and connected the two lines. And same as last time the ring started changing colors. Now as the ring glowed Luna started screaming in pain again, but instead of her turning into her, the black mist rose from her body again and flew over to the altar.

“No! Not again!” Agony was about to erase the circle but before she could the mist formed its own circle using its self.

“That, that looks like the transformation circle” Agony whispered to herself. "You know what, you can take Luna back, if I can’t rule side by side with my idol, I’ll rule on my own."