Nightmare Fuel / Fallout: Equestria - Project Horizons

• The top floors of the Fluttershy Medical Center.
  PLAY.
• Blackjack gets a first-hand view of how the Enclave mark dashites. Their cutie marks are burnt away by chemicals strong enough to produce smoke, and the fresh wounds are then immediately branded. Worse, this happens to Morning Glory, arguably the most moral character in the story, who is completely loyal but being set up for political reasons.
• Enervation. It's completely undetectable, except through its effects, and even minor exposure is enough to degrade healing supplies over time. More serious exposure results in internal bleeding, and existing wounds worsen rapidly. At high concentrations, victims suffer from Mind Rape and melt.
  • Enervation is practically alicorn kryptonite. They percieve it as a constant psychic screaming which breaks down their Hive Mind. Only Lacunae is resistant (but not immune) to its effects,^note Emphasis on "only"; the reason it causes so much damage is because if there's two or more Alicorns present, the screaming will echo between them until they shut down. and even the Goddess is tormented by it. When Lacunae is briefly exposed to an Enervation source at close range, all of Unity is injured by it.
• Stable 90 was registered as complete and ready for habitation, despite having none of the essential fixtures or equipment installed. When the bombs fell, the residents were trapped inside, descending into barbarism and dying off completely in under a month. The ponies of Stable 99 would have suffered the same fate if Blackjack hadn't gassed them all.
• Chapter 22 is rife with nightmare fuel. The first thing Blackjack sees is her mother's decapitated head, and it only gets worse from there.
  • Rampage being chained down and Eaten Alive. She's clearly traumatized, even though she 'dies' every other chapter.
  Rampage: You want fear? Fear is being strapped to a table as a permanent lunch for a bunch of cannibals. Knowing they’re going to rip you apart and eat you over… and over… and over again. Fear is knowing you might spend years or centuries that way, your flesh fueling the nightmare and you helpless to stop it.
• All of final scene of Chapter 26, especially Glory's wing falling off, and her reaction to it.
  She slowly picked it up and held it in her hooves. “It fell off…” she said with a whimper, like a foal whose favorite toy had broken. She started to shake, at first with tears… but then she threw back her head, laughing hysterically. “It fell off! It FELL the fuck off!” And with bloody tears she laughed and sobbed at the same time. “We’re going to die! We’re going to die! Please let us fucking die!”
• Chapter 30, where the taint building up in Blackjack's body causes a tumor to grow in her eye socket, forcing Glory to perform emergency surgery and get it out.
• Horizon Labs' cryo room, where a number of ponies have been melted and fused with the walls and equipment, screaming. The room is practically soaked with taint, and tries to absorb Blackjack, almost succeeding. Now illustrated.
• Blackjack's various nightmares, particularly the one in Chapter 33. Blackjack wakes up, apparently whole and healthy, in a Bad Future where Hoofington has become a monstrous world power. Blackjack's friends have all met awful fates - Rampage has lost her mind to the Angel of Death, Scotch Tape is a breeding slave, Glory is an inequine mutant, Lacunae and all of Unity have had their minds completely wiped out, and P-21 is behind it all.
• Chapter 33 begins with a disclaimer warning readers of a particularly brutal scene. Said scene involves Blackjack, who is blind and practically immobile, being mutilated^note  - her useless, mutated legs are nailed to the floor and her horn is smashed off - and gang-raped. The entire ordeal is narrated from BJ's sightless first-person perspective. There is no Rape Discretion Shot (though the hour-long ordeal is summarised in a couple of paragraphs). Scotch Tape, who is hiding in the hold below, overhears everything.
• Priest's death at Sanguine's hooves. It brings to mind this◊ (NSFW and graphic) picture of a Hiroshima survivor.
• Blackjack's encounter with pink cloud results in a fair degree of Facial Horror, including a self-inflicted Glasgow Grin after her mouth is fused shut. Illustrated here◊. (NSFW, bloody)
• The visual representation of Blackjack's traumatised, suicidal mind.
  'Glory': It doesn't have to be dark. Your subconscious is... terrifying.
• Hightower. A fortified prison filled with thousands of ghouls, most of them trapped in their cells. Not all of them are feral. The building's also bathed in powerful enervation fields and radiation, not to mention the sentient acidic ooze living in the plumbing and the malfunctioning balefire bomb in the central chamber. It's also on fire.
• In Chapter 62, Blackjack voluntarily - though not willingly - enters Lighthooves' cyberpony enhancer and "upgrades" herself into being a cybernetic alicorn. This despite her knowledge that Cybernetics Eat Your Soul. She's fully conscious while the device implants wings into her back, strips the skin off her face and covers almost every inch of her with metal plating. Yikes.
• Also from 62, the implosion megaspell that Blackjack sets off. It creates a massive vortex that is enough to destroy practically all of Shadowbolt Tower - a monstrosity whose size can be measured in miles - and crushes it into a little sphere.
• The individual fates of Macintosh's Marauders are all horrible enough, but in the Project: Horizons universe, it can always get worse. It's eventually revealed that, shortly after enlisting, the platoon spoke to a zebra fortune teller and learned that they were destined to die pointless, meaningless deaths shortly into the war. He then offered to rewrite their fates, an offer they accepted. He did this by using the Black Book (yes, that Black Book) to alter the collective fates. But there was a price: if any of them broke their fellowship, they would each suffer a Fate Worse than Death, with only the culprit receiving a peaceful death. So, of course, that's what happened: when Big Macintosh decided he was going to retire from the Marauders and settle down with his marefriend Twilight Sparkle, that was the end of everything.
  • As the one who broke the pact, Big Mac got the gentlest death; he was shot by teammate Psalm during the Battle of Shattered Ridge, but it was believed he made a Heroic Sacrifice Taking the Bullet for Princess Celestia, resulting in his being honored as a martyr.
  • Psalm herself went mad with guilt and allowed herself to be manipulated into enacting Operation Partypooper: a series of tactical assassinations on the day the megaspells hit Equestria that she believed were supposed to be preventing a coup against Princess Luna, but in fact was getting rid of anypony who could bring the Ministry to trial for their many war crimes. Then she was assimilated into the Alicorn Unity, where she became the dumping ground for the collective guilt and suffering of the Hive Mind.
  • Stonewing was officially killed in action in battle, but secretly was retrieved from the battlefield, alive but brain-damaged. Then he was fused with a cockatrice as part of Project Chimera, transforming him into a savage, near-bestial Mix-and-Match Critters. He'd still be alive 200 years later, until Blackjack finally kills him by feeding him tail-first through a mining rockcrusher.
  • Jetstream went mad with grief after Stonewing's apparent death, and was manipulated into kickstarting doomsday by being sent on what she was told was a rescue mission with a teleportation megaspell — instead, she blew herself up detonating a balefire megaspell in the Zebra capital of Roam, triggering the final apocalyptic exchange of megaspells that became The Last Day.
  • Doof was manipulated into raping his teammate Twist, and was sentenced to years in prison. He only got out by becoming a failed prototype for Project Steelpony, which turned him into a powerful cyborg in constant, all-consuming agony due to faulty nerve integrations, which he endured for 200 years before being destroyed.
  • Vanity was murdered by his brother Blueblood over the latter's jealousy at Vanity being Rarity's lover during the chaos of the Last Day, when the Blueblood estates were attacked by desperate commoners looking for access to a rumored hidden vault.
  • Applesnack was exposed to the Pink Cloud during the Last Day, which simultaneously turned him into a ghoul and physically fused him into his suit of Powered Armor.
  • Twist was raped by her teammate Doof, saw her wife killed, and herself was fatally injured during the Last Day, dying when she gave up the magical talisman granting her regeneration to bestow it to her wounded daughter Peppermint... and then found her soul imprisoned inside of Peppermint's body.
• The fate of Stable 99 was bad enough. Then you realize: if P-21 had a "full career" as a stud in the Stable, then why is Scotch Tape his only foal? Then he admits in passing that he saw his medical charts back in Stable 99; turns out he was the father of twenty nine foals (whether that's in addition to or counting Scotch Tape is unknown). And all of them died with Stable 99.
• In chapter 69, as Blackjack is trying to rally the denizens of the Hoofington wasteland, she proves who she is by consuming raw Flux/Taint. A skeptic insists it's a trick and, before she can stop him, he snatches the bottle from her and drains what's left. Initially, nothing happens... then the left side of his smiling mouth starts extending back down along his throat and over his ribcage, tentacles start curling out of the rift in his body, his stomach bulges and swells with worm-like masses rippling within, and his head starts to turn inside out as he flops over backwards and starts spasming. Then Doctor Triage disintegrates him with her laser pistol.
• In the epilogue, it's mentioned in passing that Dr. Morningstar's exposure to Poison Joke not only turned him from an old stallion into a young mare with a very healthy sexual appetite, further exposure to taint transformed him into a Mother of a Thousand Young which had to be stopped by the Zodiac before it overran the Hoof with an army of monstrous offspring.
  A grotesquely swollen Dr. Morningstar, fused with a golden tree, birthed a menagerie of fused creatures as she ranted and raved about her children. Candlewick, Dazzle, and Brutus faced her along with a half dozen others fighting to eliminate the horrific birthing monstrosity.