@Background Pony #5262
 

Best case scenario, we have a Super sayian style Transformation sequence, and half an episode of ponies kicking ass (in every sense of the term), all ending in a giant laserbeam of friendship.
 
At the rate we’re going, the box could be opened before the finale, with each pony finding a rainbow trinket at the end of the episode, which end up in finding their way of opening the box.

And I thought Brian Konietzko and Mike DiMartino were masters at trolling their audience…

What we’ve got so far then is that Dash will use a Daring Do novel as bait to lure in the Pony Of Shadows, then Rarity will tie it up with rainbow thread, Fluttershy will bite it on the ass with her new fangs, and Spike will kick it into a magic comic book world. Now we just need to figure out where Applejack’s big-ass apple contest trophy and Pinkie’s magic accordion fit in, and we’re set.

It shall introduce Rainbow Power into S4.

@SaburoDaimando  

That may be the first of 6 keys I believe.

@Background Pony #5262  
Actually I don’t think that would mess things up too bad, if it’s like that BP says.
 
The designs are pretty geh, but I think it’d be at least tolerable if it’s not a permanent fundamental design change.

My theory: The keys they need are not literal keys, but rather symbols of each of their respective elements. That thread is Rarity’s ‘key,’ given to her as a reward for exemplifying the very best of the spirit of Generosity.

@Background Pony #8222  
and I thought that they won’t be able to fuck this show more after making Twicorn… well it’s hasbro I should expect that

Throw-away ending gag. I’m calling it now. Its a throw-away ending gag.

My theory is that, given the ‘rainbow thread’ nature of the ‘key’, this will have something to do with ‘rainbow power’ (do a ’booru search, focusing on images 507385 and 509308); and that once all 6 ‘keys’ have been put in the mystery box, it will give the Mane 6 access to their ‘final form’ (i.e. being able to use the the EoH without the necessity of having the gemstone-infused necklaces/crown). Also the extra stars and stuff on their bodies are probably going to be temporary signatures of them using their power, and will fade out after power usage.
 
Remember though that this is all still just a theory, subject to modification and/or discreditation.

@Grieffon  
The posts must have been merged.

It’s not a key, it’s for that Rainbow thingy that’s suppose to appear in a future episode.

@RIG  
What dupe? I didn’t see anything under the twitter tag.

Nothing, she will use it up on the broadway dresses and that’s it.

@SnowFlurry  
Sounds pretty disappointing, so that’s probably it.

twitter dupes…the worst kind of dupe…

yee yee we got it geezzzz “rainbow power” new toy line. old news are old >.>  
blah blah blah

So will they end fighting the Heartless in order to open de door to Kindom Hearts?

@A Sad Pony  
Theory: The keys are not actual keys, but will be items that are obtained through acts of their elements (Rarity’s Generosity, Dash’s Loyalty in Rainbow Falls)

Yeah, yeah.

@A Sad Pony
 
@igotnopicks
 
Patience is a virtue, my friends.

It’s where the keys are.

Meghan stahp
 
even though you aren’t going to