The apartment was much like the rest of the city: black shadows mixing in with the white color of the objects around the room to form irregular shapes. Along one of the walls were windows that lined it to let the occupant gaze out into the seemingly endless rows of building that housed the ponies who called Mirror City home. On the far left corner formed by the windows merging with the wall sat a queen-sized bed, an Earth pony as white as her surroundings resting on it. Myrtenaster had just recently finished a series of concerts at Mirror Hall — at which she sung spectacularly — and was giving herself a moment to relax. Her long, white mane was pulled back into a ponytail so it wouldn't get pulled when she moved around, and the musical notes on her flank seemed to slightly move as she slept. Over her left eye ran a mysterious scar, nopony but her knowing where it came from. Her peaceful moment would end, though, as a crash came from outside of the room. It startled Myrtenaster and woke her up from her rest, her light blue eyes darting every which way to find the source of the noise.
"Hello? Who's there?" she called out, getting out of the bed. As she walked across the floor, squares of light appeared under her hooves where she stepped. Myrtenaster grabbed a vase and held in front of her as a makeshift weapon as she approached the door, unaware of what was out there. When she opened the door, though, she found the hall to be empty. "That's odd…"
The words barely escaped Myrtenaster's lips before she felt her body slip through the floor and flip over, her hooves landing on cold stone. She found herself in the foyer of White Castle, the alternate world that gave meaning to Mirror City's name. A sheath with a rapier was now strapped to her right side, and her cutie mark had changed from musical notes to a strange rune. In between the two sets of stairs in front of her stood three empty suits of armor — all built for more humanoid species — holding various weapons. One bore a sword as its weapon of choice, another chose a morning star, and the last decided to own stronger armor rather than a weapon.
"Oh no, not again," said Myrtenaster as the suits of armor came to life, menacingly swinging their weapons. The third suit of armor attacked first, barreling forwards at surprising speeds to slam into Myrtenaster, sending her flying into the wall behind her. The impact made her whole back burn with pain, and the following fall brought it to her stomach. "So, you want to play fast? I can do that."
Myrtenaster slowly stood up, the pain still stinging, and waited for the armored juggernaut to reach her again. When it did, she quickly waved her right hoof and teleported slightly behind it, letting it crash into the wall and get its right arm trapped in the stone. She chuckled a little before turning back to the two remaining enemies, who had closed the distance between them and Myrtenaster quickly. As the first knight swung its sword, the mare leaped into the air and gracefully curled her back over the blade. She then waved her right hoof again, which materialized the same rune on her flank right behind her hind legs. Drawing her rapier with her left hoof and grabbing it in her mouth, Myrtenaster leaped off the platform and lunged at the knight, slicing at it and causing it to burn up in a white flame as it fell to the ground.
Myrtenaster landed softly on the stone floor in front of the only active armor golem as the rune dissipated, leaving it time to draw its morning star back and swing at her with all of its might. Just as the spiked ball was about to crush her ribs, she teleported behind the suit of armor and spun a colored mechanism inside the hilt until the sword glowed blue. Myrtenaster then waved her right hoof above the ground — which placed a blue rune in the same place — and jumped back before the suit of armor could crush her with its weapon, leaving it to stick into the ground. The empty knight looked up at Myrtenaster just as she held the same hoof in front of her, a smaller version of the rune on the floor appearing. She then activated the rune below, causing it to turn to yellow and send the armored golem flying into the ceiling, cracking its armor in several places and effectively defeating it.
Myrtenaster sheathed her blade and weakly said, "That… was harder than before." She turned around and began trotting off to one of the two flights of stairs until the sound of crumbling stone caught her attention. Swinging around, she saw that the juggernaut had freed itself and was ready to fight once again. It dashed off towards Myrtenaster, leaving her little time to draw her rapier and parry the suit of armor's attack. As she jumped off to the side, her enemy had slid in the opposite direction, bracing its legs in order to stop its momentum. Myrtenaster spun the chamber again — the blade glowing red this time — and held it in a defensive position in front of her as the juggernaut charged once more. When it collided with the sword though, it stopped dead in its tracks and staggered back, the rapier being as solid as a wall of steel. Myrtenaster took the opportunity to slash away at the weakened chest plate, each blow cracking the armor a little bit more.
When the armor was sufficiently weakened, Myrtenaster took her rapier and plunged it deep into the juggernaut's chest, leaving a gaping hole on both sides of the torso. It stumbled back, clutching at the hole where the armor previously was, then fell to its knees. Myrtenaster stood over her foe — rapier readied in her mouth — as it silently begged for mercy. Knowing better than to trust the enemy, she gave a smirk and swung the blade across the helmet, letting it clatter to the ground before it and the rest of the armor burned up in the same white flame as its ally.
"Now, time to find my way out," muttered Myrtenaster as she sheathed her rapier. She trotted up one of the flights of stairs and opened up the large door at the top, ready for whatever challenge White Castle gave her next.