I hate these demons, so darn blood thirsty. Thankfully they are low level individuals that are very susceptible to fire. Well if you heat a rock in the right way it can melt. As can a blended being of rock and flesh.
Hand to hand combat with these demons is not recommended, it is like fighting a body building mass of rocks. They are hard to beat hand to hand, but with some wit and magic they are easily remedied.
One to five Quake demons in a group; can be considered a low level threat, not great but you don’t want more than five. Their build and nature are capable of natural disaster. Which is why six to thirteen gathered is a medium level threat to the nature surrounding them. At this point their power is enough to cause significant damage to the environment. If more gather and combine their efforts expect serious natural disasters to follow.