A Reiver is a specialist within the Vanguard formations of the Primaris Space Marines, a warrior trained in the arts of terror, infiltration, and psychological warfare. Where the battleline Marines break the enemy through disciplined firepower, the Reivers are sent to unman the foe entirely, striking from the shadows to sow panic behind enemy lines.
Clad in stripped-down armour and often bearing skull-faced masks, Reivers deploy by grav-chute, grapnel launcher, or subterranean tunnel to appear where they are least expected. Their masks broadcast bone-shaking screams that shred the courage of even hardened veterans, and they fall upon sentries and command posts with blade and carbine before melting away into the dark once more.
Drawn from the Vanguard companies, Reivers embody a colder, more predatory face of the Adeptus Astartes than the heroic ideal so often venerated. They are hunters of the night, weapons of dread deployed to make the enemies of Mankind fear the darkness itself long before the true assault begins.