Codex: Chaos Space Marines (2007), p23 — The Planet of Steel

Lying just outside the Eye of Terror, close to the stable warp route known as the Cadian Gate, Brigannion Four has been claimed not only by the Night Lords but also the Black Legion, the Death Guard, the Sons of Hate and the Brotherhood of Blood. It is now an unimaginably vast fortress of corrupt magic and machine, made all the more impregnable by its current ruler, Manneus Drath of the Iron Warriors.