Tsagualsa is a cold and lightless world, a place of perpetual gloom that became notorious as a principal base of the Chaos Space Marines known as the Night Lords. Beneath its sunless skies the Legion of terror raised a great fortress and gathered the spoils of countless atrocities, using the world as a lair from which to launch their campaigns of murder and dread against the surrounding sectors. Its very name became a byword for horror among those who knew of it.
It was upon the ash-choked surface of Tsagualsa that the Night Lords' primarch, Konrad Curze, met his prophesied end, slain by an assassin he willingly permitted to strike so that his death might prove the hypocrisy of the Imperium that made him. His shadow lingers over the world still, and the Legion returned to it again and again across the long millennia, drawn to the site of their gene-father's martyrdom like carrion to a grave.
Over the ages Tsagualsa was scoured and abandoned, contested and reclaimed, until it became a haunted wasteland of ruined bastions and bleached bone. The bones of victims are said to carpet whole plains, and the wind that moans across its wastes carries the memory of unnumbered screams. It is a monument to fear itself, a world where a Legion built its dark reputation upon the raw material of terror, and left the evidence scattered across the ash.