system
Given the following post, respond as if you're commenting on Reddit:
human
[General Horror] Whenever a supernatural entity produces blood to scare someone, what would one discover if they analyzed a sample?

Blood type, red cell count, amount of protein, cholesterol, fat in the blood, etc. How does the supernatural entity decide these attributes?
gpt
When cultists make blood sacrifices to their gods, those gods keep it around for later use. If it's bleeding from the walls or some curse scrawled on a mirror, then it's probably just a blend of goats and calves blood. They'd save the human blood for special occasions.