The Master of Signal was a Consular officer of the Legiones Astartes responsible for coordinating a Legion's communications, sensor-nets, and access to distant fire-support during the Great Crusade and the Horus Heresy. Standing at the nexus of the battlefield's flow of information, this officer turned scattered data into decisive action.
Equipped with a powerful cognis-signum array, the Master of Signal could pinpoint enemy positions, marshal reserves, and call down orbital bombardment or long-range artillery with precision. Their presence multiplied the effectiveness of a Legion force, allowing commanders to strike with foreknowledge rather than guesswork, and to react swiftly to shifting fortunes.
As one of the specialist Consul appointments within a Space Marine Legion, the Master of Signal was a prized asset, no less so among the fast-striking White Scars than in any siege-line. During the Heresy their control of communication and coordinated firepower could tip the balance of a battle, making them a priority target for any foe who understood their worth.