Like a pair of synchronized swimmers, you both try to jump the other at the same time.
She's a ferocious fighter. While you're in better shape and have quicker reflexes, she knows her territory like the back of her wing.
You're nearly a perfect match for each other. She punches, you block. You kick, she dodges. She's not afraid to use dirty tricks like tripping you up with cables.
What's most worrying of all is how much she seems to be enjoying it.
"Yes, yes! I love the feisty ones!" she cackles. "Get that adrenaline flowing! And the dopamine! The cortisol! I can tell you're going to give me so much data! And who knows?" Her smile turns positively sadistic. "You might be the first to actually live through the tests."
You don't know what kind of spell she's trying to cast with those gibberish magic words, but you don't like the sound of it.
You push her up against the wall but she slips out of her lab coat and escapes. With it gone you can see the scars covering her body. She lands a gut punch in your distraction that leaves you gasping for breath. She starts dragging you towards the tub and her contraption.
Spots dance across your vision. Whatever she punched has made inhaling a terrible trial. Still you struggle to stand back up and free your tail from her grip.
A kick glances off the back of your head and you see stars.
You're still awake though, even if only barely.
"That was a hassle," you can hear her grumble, "I think she threw my shoulder out. Gonna feel that tomorrow. Lousy lookalike better give me some good Chroma for this."
It takes you a second to realize that she's talking to herself. She must think she knocked you out entirely. You can use that. You let your body go extra limp, not that it wasn't already, but now you shift so your legs keep 'accidentally' catching on every loose wire and pipe in your way. Every second she spends detangling you is another you can spend recovering.
Sooner than you'd like she reaches the lip of the tub and hefts you up over her shoulder like a sack of potatoes. She stomps on a switch and the doors to her mechanical cage rattle open. Inside is a cavity just big enough for a pony, if you don't mind sharing space with countless needle-tipped tubes and wires.
This is your chance!
As she lifts you up you grab her hooves with your own, tighten your core, and pull! She's caught totally off guard and the unexpected shift in weight overbalances her and lifts her off the ground! You're slammed into the porcelain floor with all her weight on top of you.
You tense your back legs and thrust, throwing her off you and right into the mouth of the waiting machine. Restraints snap into place instantly, locking down her legs and barrel.
"What? No!" she cries as she realizes her situation. "It was supposed to be you! Not me!"
"Why don't you give it a spin first, just to make sure it works." You stamp down on the same switch that she had.
The poorly cleaned doors of the cage begin to close, the squealing of metal drowning out most of other Rainbow Dash's screaming protests.
"No! You monster! Do you have any idea what you've done?! My plans! My destiny! You've ruined everything!" You can hear her thrashing against the cage. It rattles like shackles heavy with all the blood on her hooves. "You can't do this to me! I was supposed to ascend! It's my destiny! I just needed a little purer Chroma! This isn't what she promised me! Noooooooo-!"
Her final scream is cut short as the iron doors slam shut and seal.
Meanwhile, all the machines around you are coming to life. Electricity arcs from one electrode to another, hissing and snapping like snakes. Pumps slowly coming to rhythmic speed and start driving fluid through the many pipes.
From deep in the walls, you hear a final piercing scream.
And then the facility shuts down once more.
You take a deep and let it out in a relieved sigh; the only noise among the silent machines.
*Ding!*
You flinch as the ill-fittingly happy chime tweaks your still agitated nerves. But it's over now, You no longer have to fear your evil clone trying to grind you into Rainbow Juice.
As if on cue, one of the machines beside you rattles then dings before opening a sliding hatch. Inside is a slim glass vial capped with a cork and filled with a rainbow liquid. Even as you give it a shake the colors don't mix and quickly separate back into layers. A small label on it reads 'Warning! Experimental Formula'.
You shudder as you try to remind yourself that it's only just a prop made by Starlight. Not the actual liquified magical remains of the pony you just fought with and threw into her own torture device.
You notice on the inside of the opened panel there's a small placard. It reads:
The inspiration for this room was drawn from the winning entry to the Ponyville Young Horror Writer's Club Nightmare Night short story contest. To read the story in full, come visit us Tuesday and Thursday evenings in the schoolhouse annex from six to eight. Ask for a copy of 'The Rainbow Fracturing' by Scooting Along and Aura Dog.
You have no idea who the latter is, but the pen name of the first pony is so obvious you can only wonder why she bothered. Sometime soon you need to have a long chat with that filly about unauthorized use of other ponies' likeness.
You tuck the vial of Experimental Formula into your Inventory and head for the door.