The scariest elements are often related to the atmosphere. Dark, damp, and cold places tend to create a sense of dread. For example, in an abandoned underground bunker, the lack of light and the stale air can make you feel claustrophobic and scared. The idea of the supernatural is also very scary. If there are rumors of ghosts or other unearthly beings in the place being explored, it heightens the fear. Also, finding things that are out of place, like a child's doll in an old factory, can be really creepy. It makes you wonder how it got there and what it might mean.
The isolation is a really scary element. When you're in an abandoned place like an old building or a tunnel, you're cut off from the normal world. There's no one to help if something goes wrong. Another is the unknown history. You don't know what happened there in the past, whether it was a place of death or some kind of cruel experiment. The strange noises also add to the horror. They can come from anywhere, and your mind starts to imagine all kinds of terrifying things that could be making those noises.
The idea of the supernatural is really terrifying. For example, in the 'Crying Baby Bridge' legend, the thought of a ghostly baby crying from beyond the grave is spooky. Also, the lack of control. When faced with something like the 'Slit - Mouthed Woman' in the story, the victims have no real way to defend themselves or escape easily.
The unknown. In the city, there could be all sorts of things lurking in the shadows. Maybe it's an abandoned building with a dark past or a hidden underground space. You don't know what you might stumble upon. It could be a homeless person with malicious intent or some kind of supernatural presence. Like in one story, a camper found a hidden basement in an old building he was camping near, and when he went down, he felt an overwhelming sense of dread for no obvious reason.
The scariest element could be the sense of the unknown. For example, in many stories, there are strange noises or happenings that the characters can't explain. It's that not - knowing what is causing the fear that really gets to you.
The isolation in many of the stories is really scary. Like when a character is alone in an old, abandoned building, cut off from the outside world, and they start to feel like they're being watched by something malevolent. There's also the fear of the supernatural, such as ghosts or demons that defy the laws of nature. This makes the characters, and the readers, feel powerless against them.
The feeling of something alive when it's not supposed to be. Like in the story where the wig moved on its own. It gives a sense of the unknown and something that defies natural laws.
The sense of helplessness is very scary. Just like in a dream where you can't run away from the threat no matter how hard you try.
Isolation can be a really scary element. In summer, people often go to remote places like cabins in the woods or lonely beaches. If something bad happens, it's hard to get help quickly. For example, if a killer is on the loose in a secluded summer camp.
The idea of malevolent forces that seem to be out to get the agents is also very scary. In the stories, there could be a force that tries to mislead the FBI, like making false evidence appear or causing distractions. It makes the agents question their own sanity and the reliability of their investigation methods. This struggle against an unseen and malicious entity is a classic horror element in 'FBI Horror Stories'.
The unexpected reactions are quite scary. For example, when smudging is supposed to cleanse but instead attracts negative entities. It's like the opposite of what is expected is happening.
The unknown is a really scary element. For example, in many RPG horror stories, there are dark areas where you don't know what's lurking. It could be a monster or some kind of evil force. Another scary thing is the sense of isolation. When your character is all alone in a spooky place, like a deserted mansion or a haunted forest, it creates a lot of tension.