A Master of the Signal will commonly be attached to the forward elements of an Adeptus Astartes assault, providing communications support across the wider warzone, and is capable of calling down a pinpoint bombardment from either orbiting fleet assets or static artillery positions nearby, engulfing the foes of Mankind in flaming destruction.
The rank, then known as Master of Signal, reached back to the time of the Space Marine Legions during the Great Crusade and Horus Heresy eras. Ranked below the Praetors who commanded the massed ranks of the Legiones Astartes into battle, was a substantial cadre of battle commanders and officers who controlled and coordinated hundreds of thousands of Space Marines across a given conflict.
Commonly referred to as Centurions, more specialised officers and ranks were also included under this level in the Legions' chain of command. The Master of Signal was one such commander at that time.