A Praedator is a daemonic creature of the Immaterium that appears in the material universe as a twisting, distorted entity with a strangely hideous and amorphous form hidden beneath. Utilised as a weapon in the arsenal of the oblivion cult known as the Starry Order, it is often summoned from the Aether through a mystical portal in order to relentlessly search for the cult's enemies, and slay them most unmercifully. This vile creature can dismember an unfortunate victim with fearsome speed and strength. There is very little defence against such creatures, as it is almost impossible to destroy one or turn it aside -- and even then, another Praedator will emerge from the next portal a victim passes by.
The Starry Order is a conspiracy of oblivion cults that spans the Ixaniad Sector. Its Heretics teach an apocalyptic creed -- and for a standard century its fanatics have turned their eyes to the Calixis Sector and the Tyrant Star. Not content to merely preach, they seek to bring an apocalypse crashing down upon all. The worst of these cultists carry degenerate secrets into the Calixis voids, seeking greater sorcery with which to destroy worlds in Empyreal flames.
Upon a blasted xenos world in the 7th century of the 41st Millennium, Starry Order archeoexplorators found what came to be known as the Conceit -- a concept that is also a key to an ancient and potent pact made between an unknown xenos species and the Warp. To know the Conceit is to become visible to the Praedator, malign ripples of the Warp given form as an implacable, invisible hunting beast. These daemons search relentlessly and slay mercilessly, vanishing only when all who knew the Conceit are dead and torn. Starry Order seers came to understand the cursed daemon–key, and it became a weapon in their arsenal of vile sorcery. The Conceit presently takes the form of a scroll of High Gothic script and some few diagrams, but it can also be explained verbally. Study or discussion of at least a solar hour is required to comprehend it, but that is usually longer than any would–be tutor has left to live. A psyker who knows the Conceit can project that understanding into other minds instantly, should his talents lie in that direction.
Once the Conceit is learned, a Praedator will soon come from the Warp to slay and rend. The Praedator perceives the Materium through portals -- any door, archway, or other method used by people to traverse an enclosing wall -- and are constrained to materialise at a portal. A new victim of the Conceit is safe for so long as he goes nowhere near a portal of any sort, or remains forever enclosed like the vat–psyker slaves of the Starry Order.
A Praedator appears in the Materium as a series of twisting distortions of the air, with the barest suggestions of a hideous, flowing, amorphous form hidden beneath. Its invisible protuberances lunge and dismember with fearsome speed and strength. The daemon will not hesitate to slay anyone who comes within reach while it tracks the mind–scent of the Conceit. A Praedator is absolutely silent, even in the midst of tearing apart men and beasts that stand in its path. Very little can destroy it or turn it aside — and even then, another Praedator will emerge from the next portal the victim passes by. There is no escape whilst the Conceit remains known.
This daemon is a reference to the Hounds of Tindalos, otherwordly entities created by the author Frank Belknap Long -- both creatures are hellbent on killing individuals that possess some particular knowledge -- but they are able to access reality only through a specific medium, and both have hardly discernible and hideous forms.
- Dark Heresy: Creatures Anathema (RPG), pp.127-128