A ghost stalks the promethium sprawl. A pale shadow of death, a blur of blades, a haze of red, misty blood.
The first reports from Space Marine scout detachment P-733 were only of strange noises and creepy feelings. A blast of cold air throughout the steaming pipes, the hairs on the back of their necks standing at attention, the echo of a faint stoccato beat... what they could only describe as laughter. A sound totally devoid of joy, instead dripping with malice. They evacuated the area with extreme haste.
The second report came from Logister Olgin Devros, tracking threat assessments through security recordings. He began his mundane task as usual, noting a band of nine Orks entering section TK-421 in search of spoils. But when their guns began blazing, firing shells seemingly at random in the dark, his attention grew. It certainly wasn't unusual behavior for Orks to rowdily brawl and fire their weapons amongst themselves, but then they began falling. One, two, three all at once! Green, fungus-filled blood spraying and coating the walls. Devros watched in growing horror as within minutes, the entire warband was dispatched.
Devros reviewed the tape, again and again, finding nothing. It was as if a wind blew through the sprawl, assailing the greenskins. A wind that could turn corners, climb ladders, and target each Ork one-by-one, slicing open arms, legs, and necks. His servitor mind had no reference to equate this, his human mind no way to rationalize this. He was watching a ghost. An invisible, unstoppable, murderer unbound by weapons, strength, even gravity itself.
Upon reporting his findings, Devros was assigned to techseer maintenance for a diagnostic mindwipe. Clearly he had malfunctioned and altered the recording, though to what end, the Mechanicus priests were not able to discover. Perhaps the pervading promethium of this wretched world simply corroded his circuits. It matters little now.