The Keys of Hel were the seals placed upon forbidden technological knowledge by Ferrus Manus, Primarch of the Iron Hands Space Marine Legion during the Great Crusade era of the late 30th Millennium. These included the true rites of cybernetic resurrection. Where such elements of forbidden technology or lore were encountered (and indeed recognised for what they were only by the Iron Hands), they were seized and suppressed by the Primarch's express order and withheld, it was rumoured, even from the Mechanicum. Few outside the X Legion knew of the ban placed by Ferrus Manus on such forbidden technology as the Sarcosan Formulae, the Progression of the Seventh Gate, and the Ophidian Scale. Even amongst his sons few knew more than the name and, of those who did know, most grasped only the shadow