The Emperor's Embers are a strange and poorly understood resource. There is a finite number of them in the world, though this may not always have been the case.
Legend tells that they were the blood, sweat, and tears of the God-Emperor who once built and ruled the world. On their own, they are rather useless, dully colored stones. However, if one with The Gift were to happen upon a stone, it could spark to produce a warm glow--like a hot ember.
In this state, the stones are capable of great and terrible things. Back when the God Emperor was said to rule, these stones powered his entire civilization. They served not only as an energy source, but also as tools upon which any one of a wide manner of purposes could be ascribed to. So too, did they serve as archives which could hold tremendous amounts of information and project it to those who would seek its secrets.

Nowadays, it is only those with The Gift who can manipulate these old stones and breathe life into them once more. They are the Soothsayers, the Oracles, the scryers...those fabled to be the direct descendants of the God-Emperor himself, and in their veins, house his blood.