Where and when it shows up
Wallpaper-like camouflage. Spawns in groups of 1 to 6, in rooms and hallways.
Hiders are the one monster where item management matters as much as combat โ holding literally anything (even something low-value) changes the outcome of a grab from a sanity hit to an item loss you can afford. Worth carrying a spare cheap item specifically for this reason if you're heading into a room with reported Hider activity.