Eberron - Return of the Lich Queen
Ancient legends and creation myths describe Eberron as a world in three parts, the ring above. the subterranean realm below, and the land between. Each of these world sections is tied to a great dragon of legend Siberys, Khyber. and Eberron. Each section of the world produces stones and crystals imbued with arcane power—dragonshards. With dragonshards, dragon marks can be made more powerful, elementals can be controlled and harnessed, and magic items of all sorts can be crafted and shaped. These shards, however, are rare and difficult to come by. making them expensive and often the goals of great quests and adventures.