Phobos Worked in Adamant (Warhammer 40,000)

Celare Artum is a world on the edge of destruction. Abaddon the Despoiler’s most potent weapon, his Planet Killer, is on its way, and the forge world is going to die. One man holds the key to saving the planet. An unorthodox member of the Adeptus Mechanicus, Magos Ghuul has a device that can stop the Planet Killer... if the rule-bound adepts of his ancient order will let him use it.