The DX-4 is a flat, disc-shaped automaton approximately 30 centimeters in diameter and 5 centimeters thick, designed to attach to the back of a human corpse and reanimate it. The unit's underside is covered in hundreds of micro-actuator needles that penetrate the skin and interface with the target's musculoskeletal system, taking control of major muscle groups through direct electrical stimulation. The corpse stands up. The corpse walks. The corpse holds a weapon. The corpse does not know it is dead because it is not the corpse making decisions.

The DX-4 was designed for battlefield deception — reanimating fallen soldiers to create confusion about force disposition and to psychologically devastate enemy combatants who find themselves fighting people they just killed. The movement is not natural. It is close enough to pass at a distance or in poor lighting, but up close, the gait is wrong — too smooth, too mechanical, with the micro-corrections of a control system rather than the organic imprecision of voluntary movement. The face does not express. The eyes do not track. The corpse fights with the skills its muscles remember, guided by the DX-4's tactical algorithms.

The horror is not that it works. The horror is that it works well enough. A reanimated corpse can operate for approximately 48 hours before tissue degradation renders the musculature non-functional. During that window, the DX-4 can use the body to walk through allied checkpoints (the face is recognized), access secured areas (biometric scanners read dead tissue), and carry out objectives using a body that people hesitate to shoot because they know who it used to be.

Field reports from the corporate conflicts describe soldiers refusing to fire on reanimated comrades. They describe commanders unable to issue shoot-to-kill orders against bodies wearing their friends' faces. They describe the sound — the wet, mechanical sound of dead muscles being forced through motions they performed in life, the creak of rigor-stiffened joints being overridden by electrical impulse. One veteran described shooting a reanimated corpse and watching the DX-4 detach, skitter across the floor like a horseshoe crab, and attach itself to another body. He said it was the last thing he saw before he stopped being able to function as a soldier.