- Shirou stumbling upon vampire victims for the first time. Not just for the standard zombie apocalypse factor, but also for the small insight we get into his mental process for not being able to make it in time to save the first victims.
- How Louvre kicks the bucket. Truly horrifying, it nearly feels like a slasher movie turned on its end with the human actually Horrifying the Horror.
- First, Shirou gets rid of his regeneration power by forcefully binding his time stream to Gaia's. This has Louvre doubt his sanity.
- Then, Shirou bestows upon him the full extent of what the cursed sword Kiritsugu is capable of: not merely crippling magic circuits, but even the SOUL, therefore destroying memories. He ends up an undignified, blubbering mess that is just scared witless of Shirou, before being finished by his Storm of Blades.
- Some Dead Apostles missions Shirou had to deal with.
- Witch!Caster turns her Master into a living wand—which involves putting her in a test-tube, unable to scream or move.
- Chapter 37 mentions a Sealing Designate who tried to make Pokemon. Harmless, right? Then we get to know what happened when they found it:One intern had made the mistake of trying to pet one of the little monstrosities. A little yellow rat. After she had been electrocuted with enough amperage to literally fry her heart, nerves and brain, no one else had hesitated in crushing every little mistake that met their eyes into a chunky red paste.
- Shirou being a very unique hybrid case of... an Incarnation of the sword element, a Living Apostle, with taint from dragon, monster, and divine blood, and protected by a very powerful Fae artifact... This makes for a very peculiar regeneration process when all of these bits work together to fix his body as it gets broken in more and more... creative ways. For example, the sight of him regenerating a blown up heart out of blades causes every Servant on the scene to pause in abject incomprehension or outright disgust, even outright monsters like Rider.
- Shirou's Apostle instincts acting up when he runs on fumes and instinctively making him want to bite anyone close.
- Assassin!Kiritsugu's situation. Not only he's forced to serve the whims of a mad witch, his children are contestants in the Holy Grail War, meaning he could be forced to hurt them. The scene where he almost uses an Origin Bullet on Archer - a future version of Shirou - is nothing short of Adult Fear.
- Archer's past is this for Rin, moreso when he reveals he was executed and she was probably right there.
- Shirou's reaction to seeing Archer and taking in the whole of his life and existence as a Counter Guardian, reduced to a blurbing, quivering mess, finally realizing what Kiritsugu wanted to prevent, only able to profusely apologize.
- Witch!Caster messing around with Sakura's curse in front of Archer:
- This could have led to a berserk shadow unleashed with all the nightmare factor from the Heaven's Feel route.
- Or push Archer into killing (likely again!) Sakura to save the world.
Nightmare Fuel / From Fake Dreams