13th Founding - 13th Founding: The 13th Founding, also known as the Dark Founding, occurred sometime between the 35th and 36th Millennium, and is one of the very rare Foundings of Space Marine Chapters that were not recorded in exact detail.Since the Horus Heresy, the Adeptus Terra has maintained a bank of original gene-seed tithed by every single Chapter ever created, with one notable exception: the 13th Founding. There are no reliable records that indicate how many Chapters were created during the Dark Founding or what became of them.Full disclosure of the exact details of this mysterious Founding may lie buried deep within the record office of the Adeptus Terra. One Chapter known to have been founded at this time is the mysterious Exorcists Chapter, though there are two suspected Chapters created during this unrecorded Founding -- the Death Spectres and the formerly-Loyalist Crimson Sabres.The exact nature of the Exorcists' creation and the gene-seed used in their Founding has remained classified by a special Bull Absolute of the Inquisitorial Representative to the Senatorum Imperialis issued at the time of their Founding. The Chapter has long-standing and strong links with the Inquisition and certain factions within the Ordo Malleus in particular, and it is most likely that it is the sponsorship and designs of that Ordo that has given them their unique character, and may well have specified their creation, either as a grand experiment or for some singular purpose.They are unusually resistant to both Daemonic possession and Chaos corruption. As part of their initiation into the Chapter, Exorcists Astartes are forced to serve as Daemonhosts for a short time before the possessing Daemon is expelled back to the Warp by the intervention of an Inquisitor.The Death Spectres are the second known Chapter to have been created during this unusual Founding. They are a Successor Chapter of the Raven Guard and share the same mutations as found in that Chapter's gene-seed. Like the Raven Guard, the battle-brothers of this Chapter possess a minor mutation that causes the Melanochromic Organ (which controls the amount of melanin in an Astartes' skin tone) to not function properly, leading to the development of albinism in Death Spectres Astartes. Additionally, due to further mutations, the Death Spectres lack a functional mucranoid and Betcher's Gland.Differing Melanochrome gene-seed from Chapter to Chapter leads to variations in skin and hair colour, and in some Chapters all of the Space Marines may have identical colouration, such as is found in the albino warriors of the Death Spectres Chapter.Finally, there is the Crimson Sabres Chapter. The Renegade Space Marine warband who call themselves the Crimson Slaughter were once the Crimson Sabres. Since their betrayal and excommunication, many have sought out the Chapter's origins, delving back into their past to find perhaps some reasoning behind their rapid decline into savage butchery.Thus far, the Inquisition has failed to reveal any conclusive evidence that links them to corrupt gene-seed or known mutagenic factors. It is surmised by many, from Inquisitors to curator-scribes, that the Crimson Sabres may have belonged to the 13th Founding, but nothing has ever been proven.