The fall of House Madrimar to Chaos was a great blow to the Imperium, for once they were the foremost experts on the Navigator Gene and its effects on human physiology and psychology. Yet, it was not unexpected; they had been treading a fine line of heresy for some time, and in their endless pursuit of knowledge, they turned to the Ruinous Powers for guidance. As a sacrifice to their new lord, Tzeentch, they attacked House Sigyn in open warfare, aided by the legions of Chaos. There was much bloodshed, and that great House was all but destroyed.
House Madrimar is now feared across the Imperium, helming ships for the forces of the latest Black Crusade. They still possess unparalleled knowledge of the Navigator Gene and its mutations, and their knowledge has only increased with the blasphemous experiments enabled by the sorcerers they call allies. Thus, they have been known to allow a degree of mutation that would be grounds for destruction in less corrupt houses, some so warped as to be barely recognizable as human.
Secretly, some within the Imperium still deal with House Madrimar, as are still active in the cold trade and still possess enormous hoards of xenos artifacts. They also know of warp routes that no other possess, revealed to them through consorting with demons, which allow them to pierce farther into the heart of the Imperium than any now suspect. During these trades, they often stage surprise attacks on other Navigator Houses, weakening the Imperium and allowing themselves to reign supreme with true understanding of the Navigator Gene.
Members of House Madrimar are created according to the rules for Renegade houses. In addition, they gain the following traits:
Enemy of the Imperium: House Madrimar are traitors, pure and simple. Though it was hushed up for morale purposes, their betrayal was not forgotten. Gain the Enemy (Inquisition), Enemy (Adeptus Arbites), and Enemy (Navis Nobilite) talents.
Touched by Chaos: House Madrimar’s experimentation with mutation has granted them the power to warp flesh and soul with a touch, bringing humanity closer to their horrific ideal. All members of House Madrimar begin with the Corrupt the Flesh power.
Blasphemous Enlightenment: The Navigator Gene is the tool and toy of House Madrimar, which they have played with until it released its true mutagenic capabilities. Whenever a member of House Madrimar would gain a mutation from a Navigator Power or a Malignancy test, they may instead choose to roll for a mutation on Table 14-3: Mutations on page 369 of the Rogue Trader Core Book. By burning a point of Fate, they may choose a Mutation from Table 14-3 instead, but they cannot gain any mutation that would require a roll of 75 or above in this fashion.
*Demon Within: House Madrimar has given itself to Chaos, this is true, but they still delude themselves with the idea that they are masters of their forms. Tzeentch laughs, because he can see the terrible corruption lurking inside. Any time a member of House Madrimar gains or improves a Navigator Power, he gains 1d5 points of corruption. In addition, any time he would gain 5 or more points of corruption, he must make a Malignancy Test or gain a mutation from Table 10-8: Malignancies on page 300 of the Rogue Trader Core Book.
Augury of Visions: Before going on a journey, a member of House Madrimar may isolate a single individual for their horrific augury. They restrain their victim and spend several minutes cutting symbols of Chaos into their flesh. Then, the Navigator touches the victim and activates his Corrupt the Flesh power; they interpret the progression and manifestation of mutations to determine the state of the warp. This grants +20 to their Psyniscience test, but they must make an Ordinary (+10) Willpower test or find some of their power feeds back into them, causing them to gain a point of Corruption.