The third, and undoubtedly the worst of the three great threats to the soul of Mankind, is that which seethes and gibbers but a thought away in the unreal dimension of the the Warp. Without the Warp, the Imperium would cease to meaningfully exist. It is only by voyaging through the Sea of Souls, where the rational laws of time and space have no meaning, that it is possible to maintain a galaxy-spanning empire at all. Equally, Mankind relies upon those gifted with psychic powers for interstellar communication. Control over the worlds of the Imperium would be impossible without the Warp.
But as much as the Warp is the basis of Mankind’s dominion over the galaxy, it is also the crucible of its doom. The Warp can be likened to a raging sea made from the raw stuff of the soul. All mortals blessed with a soul have a connection to the Warp, but souls most are insignificant and offer poor sustenance to the predators that lurk within its depths. It is via the soul that the beings within the Warp interact with the physical universe, poisoning the hearts and minds of men with the unutterable madness that is their being. The connection flows both ways; for mortal passions feed the Warp, and from these concentrated storms of emotion came sentient creatures of horrid design. These are the The Ruinous Powers, manifestations of the worst excesses of living creatures. They are the secret that humanity must never know, for the knowledge of the Warp’s true nature and this soul-consuming threat would drive men to madness.
The Chaos Gods are raw desire, rage, decay, and hubris, and from terrible kingdoms within the Warp reach out to Mankind to entice and destroy. There are four great Chaos Gods: the Blood God Khorne, the God of Decay Nurgle, the Prince of Desire Slaanesh, and the Master of Fate Tzeentch. These Ruinous Powers await the deluded and desirous, granting power in exchange for souls to those who would betray their Emperor. Serving these terrible entities are their legions of Daemon. These creatures of raw Warp energy can emerge from the Immaterium to form corporeal bodies and directly kill, tempt, and enrapture mortals. Each is an impossible shape, baleful to the mind and imparting soul-wrenching fear upon all who see them. Some are summoned through foul ritual, eagerly venturing into reality and often consuming the souls of those who would seek to bind them. Others pierce the breach between real space and the Immaterium through locations weakened from bloody warfare or uncontrolled
psychic emanations. Once unleashed, Daemons are an affront to reality and, until banished back to the Warp, are a danger few can comprehend, let alone withstand.
A few are mortals raised up to the status of immortal Daemon Princes, the reward for exceptionally perverse and dedicated service to their profane god. The vast majority who tread the Path to Glory have not the strength to contain the mutating power of the Warp, however, and are transformed into Chaos Spawn; mindless beasts of tentacle and claw, forever a lesson on the fickle nature of the Ruinous Powers.