Cadance's POV
"The Tantabus." Artemisa replied gravely. Twilight and Celestia looked surprised, but Luna seemed like she already knew this. I was just confused.
"What's the Tantabus?" I asked. Luna hung her head in obvious shame, though I didn't understand why.
"The Tantabus is essentially Nightmare essence, causing the ponies it haunts to receive nightmares every night. Given enough power from enough ponies, it can essentially escape into our realm," Artemisa said. "If it were to escape, the Tantabus is a foe not unlike Discord and Tirek. It uses its power to create fear in order to attempt to steal the happiness from each pony, causing itself to grow stronger. Should this happen, this could be the destruction of many empires, including both this one and Equestria, which is why we've summoned you here for help." I nodded. That made some sense.
"How do we stop it?" I asked.
"I don't know," Artemisa admitted. "This is a Tantabus unlike any I've ever seen. Once it was banished from the dreams of Ponyville, it somehow managed to travel through the dream realm to my dream, and has manifested in the dreams of a few of the citizens of the Empire." She paused, and I noticed grey lines beneath her eyes. "I don't know how much longer we can stay awake, which is why we need the assistance of a pony who can dreamwalk." Her eyes fell on Luna. Luna nodded.
"I'll do what I can to help," she promised. "It's my fault this happened in the first place."
"I thought so," Artemisa answered. "A Tantabus has the basic power of they who created it. It just needs a stronger force to unlock it. That's the reason this one can cross dreams so easily, and needs much less power than normal to enter the physical world." She yawned. "However, now is not the time to deal with this. You'll need rest from your journey. Seeing as I am aware you two do not usually get along with your mother, I have arranged for you all to stay with another pony." She smiled slyly. She opened the door with her magic, which glowed gold.
A beautiful alicorn stood behind the door, smiling slightly. She had a yellowish-orangey coat, and beautiful, flowing, flame-colored hair. Her cutie mark was a beautiful circle of fire. Celestia gasped.
"Enya?" She cried out in disbelief, smile wide on her face.