Can you keep a secret?

Begining of darkness

Sombra approached Twilight and pushed her friends aside. She couldn't move, something in her told her not to.
"I remember you back when Cadance took my throne. You moved the crystal heart from its place, I saw you use dark magic like me. You're special like me and my daughter." He says slowly circling her.
"I'll never join you, especially not when you've taken another's form."
"Feisty one aren't you?" He said stopping in front of her.
"Release Flash now, Sambra! We'll stop you no matter what. You can't win." Twilight says sternly. He growls under his breath and walks away, urging his daughter and her friend to follow.
"You three, take care of the princess. We'll be back for her, that's a promise I plan to keep." Scarlet says looking back at the three insanity ponies. They saluted and the two followed after King Sombra. Twilight watched helplessly being held back as the darkened colt walked away toward Maretropolis.
"Flash. . ."

***

Treaty saw three silhouettes coming toward them from out of the woods. The ponies all paused in curiosity as they approached. The renewed king of darkness, followed by his two loyalists, marched through the awe struck crowd. Treaty watched as Sombra walked past her.
"What has happened? Where is the princess?!" Treaty demanded answers. Sombra eyed her and simply laughed darkly.
"Why are you laughing?! This is serious!! *gasp* your wearing the crown!!" Treaty and the ponies all backed away.
"Who you see is not the colt who came as a friend of the princess. But the king of darkness, King Sombra!" Ellei says formally.
"My father." Scarlet adds bowing her head. "Your orders, father?"
"Call upon you friends Ellei, let us take this city! Then all of Equestria!!" He says using his dark magic. A wall of slithering darkness surrounded the city. The creepypasta ponies all creeped out of a vortex in the wall. The ponies began to run in fear, trying to escape. Scarlet and Ellei joined the creepypasta and rounded up the ponies for Sombra.

Twilight and the others sat locked in the basement of Ellei and Scarlets house. They kept trying to reach through to their friends. Nothing worked.
"If only they could see for who they truly are. I know Rarity wouldn't like the new her." Applejack says.
"That's it! We need a mirror!" Twilight says with an idea.

***

"Sister! There is trouble in Maretropolis." Luna tells Celestia.
"What is it?"
"King Sombr has returned. I'm afraid he's taken on the form of princess Cadances gaurd, Flash Centry."
"Quickly we must warn Cadance and Shining Armour. What of Twilight??" Celestia asks concerned.
"Hopefully she and her friends can escape their prison. No doubt she'll think of something."
"That's not what I'm afraid of. I fear he might want more than just Equestria. . ." Celestia says looking over the horizon at Twilights castle. . .