"Leave no stone upon stone, salt the earth with the blood of the fallen and leave only ashes to mark their passing. Let Calth be the grave marker of the Ultramarines."
- — Nur Asoktan, the Butcher of Dainhold and Master of the Flayed Hand
The Flayed Hand was a Chapter of the Word Bearers Space Marine Legion. During the opening days of the Horus Heresy they were one of the largest constituent chapters of the XVIIth Legion to arrive at Calth in force. The warriors of the Flayed Hand were one of several groups of Legiones Astartes included in the assault whose loyalty to Lorgar's new cause was undoubted, even if their mental stability was now suspect. It seems likely that their zeal was intended to act as an example for those whose commitment the Primarch found to be questionable. Of the 6,000-8,000 of the Flayed Hand deployed at Calth, it is believed, through inspection of data records of the conflict and necro-cortical interrogation of the fallen, that nearly half of this number fought interspersed with other chapters as well, reinforcing their numbers and in turn their resolve to the mission at hand, rendering a truly accurate accounting of their numbers impossible.
Records and testimony gathered from within the Traitors' ranks reveal that the warriors of the Flayed Hand had enthusiastically embraced the new path of their Primarch Lorgar and showed particular interest in various occult rites and practices, and from accounts of the surviving Raven Guard and Salamanders veterans of the Dropsite Massacre of Istvaan V were responsible for a number of atrocities during that conflict, perhaps to fuel this growing obsession. Many among their number volunteered to undergo Erebus' new process for the manufacture of Gal Vorbak Warp-tainted warriors to replace those lost in battle -- a process that met with mixed results. In the years before the outbreak of the Horus Heresy, the Flayed Hand were noted for their intricately planned, multi-pronged assaults and set piece battles. In the wake of the changes wrought upon the Legion, such tactical complexities appear to have been cast aside; during the fighting on Calth, the Flayed Hand fought with a fury that disdained all except the slaughter of the foe and their ritual dedications. These dedications it seems found favour with Lorgar, but perhaps ultimately less so with Kor Phaeron and Erebus, who saw perhaps a rising and secretive power within the Legion, unbeholden to them for revelation and contact with occult truth.
At the head of the Flayed Hand on Calth was Nur Asoktan, one of many Colchisians taken into the Legion in the years after Lorgar's rediscovery. Once the architect of many of the Flayed Hand's grandest strategies, Praetor Asoktan's genius for strategy had not been abandoned as had the wider chapter's, but instead perverted into a gift for the creation of cruel and elaborate traps for his foes. At Calth, Asoktan and his men were assigned to muster among the vast manufactoria of Dainhold, and in the hours before the Campanile struck, he directed his men to begin the construction of concealed roadblocks and fortifications, under the guise of training drills. This being the least of the oddities the Word Bearers manifested in the hours before their treachery was known, and under orders from Ultramarines Primarch Roboute Guilliman himself to accommodate their allies, there was little obstruction of the work. When the battle was joined in earnest mere hours later, these obstructions were used to channel the retreat of the Ultramarines, forcing them into manufactoria from which there would be no escape. Once the warriors of the XIIIth Legion were trapped, Asoktan and his warriors then indulged in an extended torment of their foes, as did many of the other Word Bearers, stopping them from gaining any strategic impetus above the torture of the trapped Ultramarines.
- The Horus Heresy - Book Five: Tempest by Alan Bligh, pp. 33, 38, 50, 52, 105, 107, 110, 240