Alone, on the chilly tundra of the planet Kronus. You were separated from your fellows in the Imperial Guard following a harrowing defensive against attacking Eldar and Blood Ravens. As you try to find some form of elevation, to observe the geography and get your bearings, you suddenly feel the ominous scrape of wraithbone against your flak armor, as an ethereal, harmonious voice speaks to you from behind.

"Turn around, human."