The Magma Hounds are a warband of Chaos Space Marines. They were once a Loyalist Chapter of Space Marines of unknown origin and Founding, known as the Knights Excelsior. They were corrupted after entering the Eye of Terror in 321.M37 as part of the Imperial Abyssal Crusade. During their sojourn into the Eye, the Knights Excelsior found themselves on the Dark Forge World of Temporia, home of the vile Heretek and Warpsmith named Valadrak. While investigating the strange mechanically-constructed world composed of endless manufactoria and machines, they were attacked by strange, living Daemon Engines. Outgunned, the Knights Excelsior were forced to make a hasty tactical withdrawal, fighting their way back to their dropships. As the Chapter attempted to make good their escape, their orbiting wa