Oread

Oreads are the genius loci of the earth, and are guardians of the earth. They are typically bound to one sacred boulder or naturally formed menhir. When in human form they present as indigenous to that land. Oreads can travel magically through the earth by stepping in and out of large stones and boulders, and can also take on rock form. They are enormously physically and magically powerful, with great power over the element of earth, far more than any witch. Oreads can manipulate earth and rock in wide and devastating ways, even causing earthquakes and great chasms in the earth.
They are virtually impossible to kill, for their sacred rock must be utterly and entirely destroyed. If there is any particle remaining, the oread will be able to reform. The only other recorded way to kill an oread is to hold it away from the earth - they draw their power and life from the earth, so to hold them away from it results in their death. When an oread dies, it disintegrates into sand and dust.