"I can't believe this!" said Rainbow Dash.
"Discord mentioned that the mastermind behind all this might be a traitor," said Luna. "I wonder if Shadowstealth is the traitor."
"Ah wouldn't think so," said Applejack. "Whoever stole those elements set him up fer this."
"It just had to be Discord!" exclaimed Rainbow. "Who else would steal the elements to begin with! Friend or not, Discord still knows the elements are his weakness and without them, he can do what he wants! And he's the only one we know who could possibly make the sky stuck the way it is! And this makes him a traitor! It all fits!"
"As much as all kinds of evidence is directed at Discord, I think for now, we need to find a way to purge Shadowstealth of Nightmare Moon's grip!" declared Twilight.
"I agree," said Luna. She fired a dark blue beam directly at the dark tornado, but it had no effect. Twilight tried firing a magenta beam, but it also had no effect.
"Without the elements, you are powerless against me!" gloated Shadowstealth. "Now it's my turn!" He spread his front hooves out wide and dark tentacles shot out of the whirlwind, quickly ensnaring the Mane 6, Spike, and Luna. The tentacles then began to work their dark magic, clouding them in black fog. "Soon you will all submit to your deepest, darkest thoughts and become fresh, new avatars for Nightmare Moon! Equestria shall fall this day!" One by one, Twilight's friends shrieked in pain and torment, suffering from moments that haunted them the most in their lifetimes. Twilight had to relive the three moments when her friends denied her. They had laughed at her for being too studious, they shunned her at the wedding rehearsal of her brother and Cadance, and finally they sent Twilight away, treating her more like a princess than a friend.
"NO!" bellowed Twilight. "I won't give in! I am the Princess of Friendship!" Her eyes glowed white and her horn glowed magenta, preparing to cast more magic. Suddenly, streaks of magenta-colored shooting stars rained down on the dark tentacles, destroying them and also weakening the black tornado. Once Twilight and the others were free, the two princesses then shot beams at the funnel, piercing it and hitting Shadowstealth directly. The dark unicorn shielded his face with his hooves as the beams hit him, but he was eventually overpowered. Dark mist then came out of his mouth and Twilight and Luna used more powerful magic to pull it all out of Shadowstealth's body and vanquish it into nothingness. The black mist turned to dust and particles and the Tree of Harmony reappeared. Shadowstealth staggered away from the tree.
"What... what happened... to me?" he moaned.
"You were possessed by a remnant of Nightmare Moon," answered Luna. "Can you remember what happened before then? We need to know who stole the Elements and Harmony." Shadowstealth rubbed his head.
"I think I remember what happened before I was brainwashed," he said. "But I don't think I saw who stole the elements." Shadowstealth began to explain his story in a flashback sequence.
"I need to harness the tree's power to subdue the remnant of Nightmare Moon I absorbed," said Shadowstealth to Twilight.
"Of course," said Twilight. "We just returned the elements back to the Tree of Harmony."
"Good." But when Shadowstealth got to the Tree of Harmony, to his horror, the elements were no longer there. "This can't be! The Elements of Harmony have been... stolen! But how? And... why?" Shadowstealth's head was then suddenly shrouded in a black fog. "No! I can't let you take control of me!"
"The nightmare always needs a host," said the remnant. "And you make a perfect fit! A decoy!"
"What?!"
"The true nightmare resides... with the one who stole the Elements of Harmony! You thought you absorbed all of me, but a fragment escaped you! I've chosen a more suitable host... one who has the power to succeed... the Princess of the Sun!"
"No! NOOOOOOOO!!"
"I can only surmise that Nightmare Moon has played a perfect hoof in an unethical experiment to terminate Princess Celestia with the Shadow of the Dark Sun," Shadowstealth concluded.
"Ya mean Nightmare Moon still wants to exact her revenge on the Princess?" asked Applejack. "We're the ones that did away with her."
"I'm the one who created Nightmare Moon," lamented Luna. "And now she has gone to extreme measures to take my sister's life. Shadowstealth, I'm afraid I must ask you. Do you know if there's any treatment for the Shadow of the Dark Sun?"
"I only know of one way," replied Shadowstealth. "The dark magic inside the victim must be expelled from the victim's body, but I can only do it by transferring the dark magic back where it came from. Since Princess Celestia didn't learn any dark magic to raise the sun, that means all the dark magic would have to be sent back to Nightmare Moon, assuming she's the mastermind."
"Wait a minute..." said Rainbow Dash. "If Nightmare Moon is the cause of all this, why isn't it nighttime? All we've ever heard about Nightmare Moon is that she just wants eternal night in Equestria. That's all. But the sky is more in between day and night."
"Then perhaps that must be a sign," said Shadowstealth. "A clue that can point out the real culprit, or rather Nightmare Moon's host."
"But who in Equestria would want the sky stuck like that?" asked Applejack rhetorically. Rainbow Dash opened her mouth to answer, but Applejack interrupted. "Besides Discord."
"Perhaps that's not even a question that needs answering," said Shadowstealth. "We just need to find out if Nightmare Moon is somehow responsible. She still has one host left."
"And this host must have stolen the Elements of Harmony," said Luna. "But not even Nightmare Moon and Discord could have possibly retrieved them from the Tree of Harmony. The only kind of pony capable of this... is a princess."
"A princess?" said Twilight's friends at the same time.
"Yes," said Twilight. "A princess." And suddenly, there were the Elements of Harmony, surrounding Twilight. She bore a smug look on her face.
"Twilight?" asked Applejack. "Why do you have all six elements? Are ya feelin' okay?"
"I feel fine, AJ," said Twilight, smirking sinisterly. "In fact... I feel better than ever!" A dark aura surrounded Twilight and the young princess levitated into the air with an evil laugh.
"Oh no!" said Fluttershy, just as Discord arrived on the scene. "Not Twilight!"
"This can't be happening!" wailed Spike.
"But it can!" said Twilight. And using the power of all six elements, Twilight transformed into a dark and taller pony figure. Her wings grew larger and her horn longer. Her mane was a brilliant shade of twilight colors with astral patterns. Her cutie mark now had a dark cloud enveloping her symbol of magic stars. She wore a dark red crown that bore the Element of Magic and also wore dark red garments with symbols of her cutie mark engraved on them. "I... am... Nightmare Twilight!" Twilight Sparkle, the Princess of Friendship, let loose with an evil and terrifying laugh, as she was now the final host of the evil Nightmare Moon.