Call of the Vigilant
Crystal entities drop into the world from the astral plane. They must inhabit an object or structure at least the size of a coffin, and commonly infest huts, garden sheds, or similar small structures. The infested structure looks built of glass, quartz, or ice. When an entity is wounded, its rock-hard skin ruptures and oozes an oily liquid. When killed, its skin shatters and its blood coagulates into elemental earth coins.