Daemon World

A daemon world is a planet so eroded by the warp that it becomes an extension of Chaos, ruled by daemons rather than mortals. Such transformations follow prolonged exposure to the immaterium — through slaughter, ritual, or the lingering aftermath of a Warp storm — until the boundary between real space and the Warp collapses entirely. Most cluster within or near the Eye of Terror and other stable Warp rifts, where the veil is thinnest and daemonic dominion can take lasting root; their terrain, skies, and very geography answer to the passions of the Ruinous Powers rather than to any natural law.

A daemon world’s character reflects whichever god or alliance of gods holds sway over it. Worlds given to Khorne resound with unending slaughter; those claimed by Nurgle fester with plague and corrupt renewal; domains of Slaanesh indulge extremities of sensation; and those touched by Tzeentch shift and mutate without pattern. Traitor Legions and Renegade warbands frequently claim such worlds as fortress-demesnes: the Iron Warriors hold the bastion-world of Medrengard, and the Emperor’s Children are bound to the pleasure-realm of Sicarus, each citadel answering to no authority beyond its Chaos Lord or Daemon Prince.

For the Imperium, daemon worlds mark the practical limit of reconquest; the Inquisition and Adeptus Astartes generally quarantine rather than assault them, since purging a world fused with the Warp offers little strategic gain against considerable peril. They serve as staging grounds for Black Crusades launched from the Eye of Terror and as courts from which Daemon Princes and Greater Daemons rule their mortal and daemonic followers alike. Their number and extent shift with the tides of the Great Rift and the fortunes of the Long War, so no complete accounting exists; what holds true of each is that world and Warp have become one, bound to whichever power first claimed it.