Warhammer 40,000: Rogue Trader (1987), p138

The celebration of the Feast of Malediction by the Dark Angels Chapter of Space Marines. This great annual event takes place in the Seclusiam of the Dark Angels' space fortress which orbits the giant planet Delahon. The feast celebrates the founding of the Chapter by Lyyn Elgonsen at the beginning of the Imperial Crusades almost ten thousand years ago. The Dark Angels are honoured as the first Marine Chapter. They were founded by the Emperor at a time when he still lived in the conventional sense. Within the Chapter the title of the Dark Angels' leader is Custodian, an honour which acknowledges the Emperor as the Chapter's true leader. The Cup of Retribution used in the ritual is said to be the actual vessel from which the Emperor drank at the original founding of the Chapter. At the culmination of the feast, the Custodian takes a small knife and cuts his thumb so that a drop of blood falls into the cup. The cup is then passed around all the assembled fighting brethren who each add a little of their own blood. Once every warrior has contributed, the contents of the cup are mixed with wine in a number of large open barrels. The cup is then passed from warrior to warrior, each filling it and drinking from the wine in turn. This ancient ritual is sacred to the Dark Angels and it is considered a bad omen if a long campaign or sudden battle delays the feast.