Blackmoor University did not get the soulbound technology right on the first try. Before settling on synthetics, they made many attempts to bind a soul into a “normal” material body beyond its natural bounds, most of which resulted in utter failure. The bonds were not strong enough to keep the soul from dissipating across the mortal boundary. The wizard-priests were only partially successful in calling the souls back. Some returned out of a sense of duty to the Empire. Very few, either twisted by the experimentation, or simply evil to begin with, returned bent on vengeance against the scientists, and the Empire that sponsored such abominable research.
A Dragonstone Lich consists mostly of the skeleton of whichever race was imperfectly soul-trapped. The dressings can vary from ceremonial armor, to ancient Thonian finery to the ragged remains of a medico smock. Two black dragonstones are seared into the bones of the subject, one at the base of the skull, another in the solar plexus. A blue-white fog of ectoplasmic soulstuff constantly leaks from these, surrounding the lich in a hazy, chilling nimbus.
In addition to the normal Lich abilities (See Master DM's booklet, page. 33-34, RC p.188) the Dragonstone Lich can also harness the power of its black dragonstones: Rather than extracting the souls to enforce its will on others using the Soulbind power, the Dragonstone Lich drives its own ectoplasmic essence into those within 20 feet, taking control of the victim on a failed Save vs. Death Ray. A Dragonstone Lich can control twice the amount of undead due to its connection to the black dragonstone's magic.
There is a 60 percent chance that any gems indicated in the lich's treasure are dragonstones. If this is the case, the lich will have full access to the stones' abilities.