The Lorekeeper's Tome

The Bone Dragon is a kind of dragon named not for what it is but for how it lives. Like all dragons it is a living thing of scale and sinew, but where another wyrm hoards gold or guards a mountain, the Bone Dragon hoards the dead - it lairs amid the bones of its prey and its slain enemies, dragging the remains of all it kills back to its lair until that lair becomes a vast hall of bone, a cathedral of the picked-clean. Some build their bone-halls in caves, some in the ruins of old keeps, some in the deep wet places where the ground swallows what dies there. They are territorial, patient, and grim, and the heaps of bone that mark a Bone Dragon's domain are warning enough to any traveller wise enough to read them. They are not common, and few who stumble into a bone-hall live to describe it.