Like, really, this would be a very interesting scene in Project Horizons sometime in the future. How Blackjack finds the door and even how she accesses the dark magic required is up to Somber to decide, but I'd like it to happen.
What would she see?
BJ SVG: [link]
Door SVG: [link]
EDIT: Don't know how that white square got there...
EDIT2: My own theory: [SPOILERS]
I theorize that Blackjack's greatest fear is not death, rape, or even the deaths of her friends, but betrayal. Although Blackjack expects betrayal from pretty much anyone, the one she expects it the least from and depends on the fact that it doesn't happen is Glory.
P-21 has already tried to turn on Blackjack, and leave through suicide. Perhaps even more than once. Blackjack wouldn't be surprised, nor confused if he did turn on her eventually. And if he died, she'd miss him, yes, but she'd be comforted that he'd be at peace.
Rampage is pretty much insane and liable to do anything, so just being around her is a risk. Having Rampage actually die would still be comforting to Blackjack as that was something Rampage has always wanted.
Lacunae still, for the moment, is under the influence of the Goddess, thus as well, Blackjack wouldn't bat an eye if the AM rifle barrel was turned on her. If Lacunae died, again, to Blackjack, death would be a comforting thought, as being the dumpster of negative emotions certainly would be a horrible burden to bear.
Scotch is feisty, and Blackjack probably sees her eventually wanting to find her own way, but still is protective of her. Many times she tries in vain to push Scotch out of her actions for her own protection, even to the point of taking the fall to make sure Scotch does not come to harm, though being all too familiar with the horrors of the Hoofington Wastelands already, she would be disheartened, but not overwhelmingly so should Scotch either turn her back on Blackjack or even die.
Glory, on the other hand, will definitely get angry, frustrated, worried, or disappointed about Blackjack and her shenanigans, but never does she leave Blackjack's side. Pretty much Glory is the only one who keeps Blackjack going sometimes, kind of like how Homage is to Littlepip. So having the support she had not only taken away but turned against her would crush her far more than just, for example, rape.
Remember, she's already confronted her fears of rape pretty much already, and is recovering, thus it isn't her worst fear. Glory turning on Blackjack, then perhaps even taking a fatal blow and pleading for Blackjack to save her before she dies would be Blackjack's greatest fear. Remember she hasn't even faced her temporary, but utter moral destruction from thinking she lost Glory in the factory collapse. So that's what I think Blackjack would see. Glory's betrayal.
Fallout: Equestria (c) Kkat
Fallout Equestria: Project Horizons (c) Somber
MLP: FIM (c) Hasbro inc.