Mordant Prime is a world situation to the galactic north of the Eye of Terror in the Segmentum Obscurus, and is known for the mining of bioluminescent bacteria from which a unique, highly corrosive acid is extracted. Mordant is classed by the Adeptus Terra as a Night World, and its surface is a barren wasteland, totally unfit for human habitation. The only reason humanity exists at all on the world is to mine the strains of luminescent bacteria that grow beneath the surface so that it can be refined into the potent acid that has many different industrial uses. Over the millennia, this process has formed a vast chain of caverns and tunnels that connect across the entire world. Within these tunnels Mordant mining clans extract the bacteria, culturing it in vast cavern-vats, to bleed off the