@DavianJ  
Maybe if Nightmare Moon had more of an allusion to Tirek, like by capturing some or all of the mane six and placing them near an AoE crystal or device that nullified magic including flight and strength, some other ponies or the remaining mane six members then rescue them from Not-Midnight Castle AKA Castle of the Two Sisters as it’s already named, and the third Midnight Castle allusion which was already included in Friendship is Magic would fulfill the climax, and subsequently did in the real Friendship is Magic. Oh, and it’d have been neat if it had a Rainbow of Darkness too, but eh. :3

I do wish MLP had thought of magic siphoners. Would have made a lot of sense for secure places. or even used them for a villain to protect themselves. Capture Rarity or a bunch of unicorns and use a crystalline structure to siphon the magic into a ward or shield. Would have made doing these pics much easier :P

@Lucky Shot  
Also, horn inhibitor rings are fan creations.

@Background Pony #4470
 
They don’t need one. The Spike Saves The Olympics episode is a proof of concept that certain facilities can have such powerful magic inhibitors built into the structure that even the Princesses are helpless.
 
What better place to implement such technology than a prison?

I always call BS in my mind when I see unicorns bound without a magic suppressor on their horn.

@Lucky Shot  
I think it’s based of Prisoner RD.

@Lucky Shot  
It’s visually appealing and fascinating to see how a cute little girl would behave in such a dark environment :)

AND YOU’VE GOT TIIIIIME.
 
Twilight is Piper, Rarity is Sophia, Fluttershy is Yoga Jones, Dash is Janae Watson, Applejack is Pennsatucky, and Pinkie Pie is Black Cindy.

I’m not saying it isn’t a distinctly possible future but why does everybody keep drawing the girls getting arrested?