Speculum Umbrae

This foul contraption was invented by the hereteks of the Empyric Engineers and, if its staggering demand for electricity is met, it enables the user to summon the shades of dead humans. The spirits that appear are at best hollowed shells of their living personality and at worst something else entirely. Sometimes these shades take an interest in the world of the living and answer questions truthfully, but more often they try to trick or even posses their would-be questioners. A summoning of this kind invariably creates a large overspill of warp energy, which contaminates all souls within a 25-meter radius of the device. The tainted energy also clings to the shades themselves, spiritually befouling any who comes in direct contact with them. For these reasons even the worst heretics tend to keep their distance, operating the device thought remote controlled servitors.

Sources

• Dark Heresy: The Radical’s handbook (RPG), pp.194-195