Malleum

Malleum is the location of Basilica Noctis, fortress and headquarters of the Void Stalkers Warband. The mighty Daemon Azazel resides within the inner sepulcher of Basilica Noctis, serving as the Void Stalkers "liason to the Dark Gods" and sometimes emerging to lead a group of Void Marines on a raid in Real Space.

History
At an unknown point, a fleet of Dark Mechanicus arrived at Malleum and constructed the artificial moon of Donn to serve as their Hell-Forge. Some time later Malleum was discovered by the Daemon Azazel who claimed the planet for his own. The DarkMech residing on Donn largely ignored the machination of the Greater Daemon.

Azazel would later lead the Angels Vigilant (now known as the Void Stalkers) to this world after their near annihilation and fall to Chaos. Soon after they immediately forged an alliance with the DarkMech of Donn and set out to rebuilt their forces. Over time the Void Stalkers built several fortresses on Malleum, the greatest of which is Basilica Noctis.

Malleum is know home to the Void Stalkers, sever groups of DarkMech from Donn, a chaos cult known as the "Disciples of Malleum", Slave Armies, Slave Workforces, and a a vast fleet of ships docked in orbit or tethered to fortress spires.

Geography and Climate
Malleum is a burning volcanic planet who's geography has been warped and exaggerated by the power of the Daemon Azazel. It mostly consists of the tall jagged mountains, charcoal or crimson plains, fire pits, volcanoes, and rivers of lava.

The sky is dark and the color of fire and blood. The Baleful Eye pierces the perpetual gloom the hangs perpetually over the planet.

Donn
Donn is an artificial moon of unknown origin that orbits Malleum. It is a hell-forge that has been inhabited and operated by the Dark Mechanicus long before the Void Stalkers came to Malleum. The Dark Mechanicus of Donn are in alliance with the Void Stalkers of Malleum, in exchange for the creation and maintenance of the Void Stalker's technology, the Void Stalkers in turn provide the Dark Mechanicus with raw material and slave labor.