The complex and often dark magic in Pathfinder horror stories adds to the fear. Magic can be used to create all sorts of terrifying situations. It can distort reality, create illusions that drive people mad, or summon unholy creatures. Also, the fact that the characters often have limited resources and knowledge makes it scarier. They might not have the right spells or weapons to deal with the horror they face. And the setting of Pathfinder, with its many strange and dangerous places, provides a perfect backdrop for horror. Old ruins, haunted forests, and cursed tombs all give a sense of impending doom.
The unknown elements in Pathfinder horror stories are really terrifying. For example, in many scenarios, you don't know what kind of monster or trap is waiting for you around the corner. It could be something completely out of your imagination.
Pathfinder horror stories are terrifying because they play on our deepest fears. They often involve themes of death, loss of control, and the corruption of the soul. The characters can be thrust into situations where they are completely out of their depth. For instance, facing an ancient evil that has been dormant for centuries and is now awakened. The sense of isolation is also a big factor. Whether it's a single character alone in a spooky place or a group that slowly gets picked off one by one, the feeling of being alone and helpless against the horror is what makes these stories so scary.