Whatever the thing is, it's getting bigger every minute, and seems to be trying to spread itself as far as it can as it climbs out of the clocktower. It takes a little luck — and some fancy maneuvering from Rainbow — but eventually they manage to slip past it, landing on the edge of the tower and making their way inside.
Applejack kicks down a couple doors and they follow the trail through the lab. The strange dark Element burns their hair and clothes, but thankfully, their metal bodies remain unaffected.
(It's still pretty gross, though.)RARITY: Yuech! Is this disgusting stuff part of that…thing?!
APPLEJACK: All ah know is that we better hurry up and find the—
APPLEJACK: Doc!!
SPIKE: Twilight!
SPIKE: Twilight! Are you okay?!
TWILIGHT: …Spike…?
TWILIGHT: What…what are you all doing here…?
FLUTTERSHY: Um, I don't think you should move too much…
RAINBOW: First things first, WHAT IS THAT THING?!
Twilight explains that she thinks it's some sort of Element, more corrupted than any she's ever even heard of before. The fact that it can move, let alone take on a shape and climb out of a tower, doesn't make any sense — but all Elements thrive off of emotions, even corrupted ones. Maybe it wants to spread itself, and whatever twisted feeling is fueling it, all over the island.
Is there a way to stop it? Maybe, if they had enough of the right kind of Element, they could counter it…but they don't have time to run tests or gather supplies, because Twilight has a much more pressing need: the wound the dark Element gave her is eating away at her body, and she needs an emergency augmentation before it spreads any further.SPIKE: But…but how are we supposed to do that?! We don't have any equipment, or a clean room, or any Elements—
PINKIE: Wait…don't we?
APPLEJACK: You mean…?
With no spares at hand, the bots decide to pool their resources, and each give up part of their own Element to save Twilight. Scrounging the lab produces enough other supplies, and Twilight and Spike prepare to walk them through the process.
[glowing intensifies]
But as they begin…TWILIGHT: Wha…?
[pop]
The five Elements, combined with the bots' desire to save Twilight, haven't just mixed — they've turned into something entirely new, which has not only counteracted the dark Element, but absorbed it. Nothing seems to remain of the monster but a mass of pink goo slopping all over the island below.
Ordinarily, Twilight would be very excited by this. A sixth Element, more powerful than she ever could have imagined, discovered by her and her friends! A strange dark Element that could move and multiply itself! If this were any other circumstance, she'd be exploding from sheer Science Joy right now!
Except Celestia's still missing, and Twilight still has a critical injury, even if it's not spreading anymore. So instead of celebrating, Twilight passes out…
This feels quite short written out like this, but had it actually gotten this far, Nightmare would've done more, and been a longer section. I had a few thoughts on things that could happen — evading her to get into the tower would've been much longer, and it would've been plenty dangerous even once they were inside (I know I wanted Fluttershy to use her wings to protect Twilight from falling goop, for one thing). I also wanted to show a bit of what was happening down on the streets as well, and how other people were reacting to this enormous drippy dragon-lady suddenly climbing out of the clocktower. But most of that is pretty vague, just ideas for moments without anything really solid yet; after all, it would've been a long time before we reached this point, so I didn't have a lot of the smaller details filled in.
I might've also given Nightmare dialogue — whether or not she should speak was something I went back and forth on a lot. A lot of my dialogue for her was very cheesy-sounding, so as it stands now I think it's better that she just makes weird eldritch noises…but maybe I would've figured out a way to make it work, who knows!