The Graviton Gun is an ancient precursor to the grav weapons carried by the Imperium's warriors, a heavy and unwieldy device that projects a field of crushing gravity upon whatever it targets. Foes caught within its influence are pressed to the ground with irresistible force, their limbs pinned, their bones ground to powder, unable even to raise a weapon before the weight claims them.
Favoured by the adeptus-mechanicus and their Skitarii cohorts, the Graviton Gun excels not merely at killing but at halting. Where it strikes a vehicle or towering war-construct, the machine is rooted in place, its tracks and legs unable to overcome the sudden and impossible mass bearing down upon it. Entire enemy advances have faltered as their vanguard was mired beneath invisible mountains of gravitic pressure.
The technology is a jealously guarded mystery, its workings encoded in patterns the tech-priests recite but scarcely comprehend. Each Graviton Gun hums with a low and ominous resonance when active, a sound that soldiers have learned to dread, for it heralds the moment when the very laws of nature are turned against them. To die beneath its field is to be slowly and inexorably unmade, flattened into the earth by a force no armour can resist.