Rissin
Rissin was a Dark Mechanicum Magos Dominus during the Horus Heresy and was among its forces that were making their way to invade Terra with the Warmaster's forces[1a]. However, when Horus learned that the Primarch Guilliman and the Ultramarines were racing to reach Terra as well, he ordered the Iron Warriors' Primarch Perturabo to send his Legion to block the Ultramarines' path. Perturabo needed the bulk of his Iron Warriors for the invasion of Terra, though, and only spared the Grand Company of Warsmith Khrossus for the task. Though it was a suicide mission with little chance of success, Khrossus vowed to do everything he could to stop the Ultramarines[1b] and Rissin[1a] and the Word Bearers High Chaplain Ker Vanthax were ordered to aid him[1b]. While the Magos was given a large force of her brethren to command[1a], the High Chaplain only led a group of four Dark Apostles. However the Word Bearers played a key part in the Warmsith's plans, as he had decided to face Guilliman in the Carchera System and needed Vanthax's power over the Warp to ensure the Ultramarines entered the System. Once Carchera fell to the Warsmith's Grand Company, Vanthax and his Dark Apostles were able to begin a Chaos ritual that narrowed the safe passage the Ultramarines were using to pass through the diminishing Ruinstorm. In doing so, Vanthax turned the Carchera System into a choke point that Guilliman would have no choice but to enter, if the Primarch intended to take part in the defense of Terra.[1b]
Sources
