"You wanna know who's in charge, sir? You see that? Yeah, the little guy with all the legs crawling over your shoe. He's in charge. He's the only one knows what the hell he's doing, anyway."
- —Specialist Vynes, 11th Ornsworld Regiment
For the troops of the Astra Militarum, few assignments are less welcomed than a posting to Ravacene. The ash-choked forests of this world are said to have given the Greyhell Front its name, and the Imperial Guard battling to wipe out the Kroot on this world fight a bleak, horrific battle against the planet and their alien foes alike.
Ravacene's ecology is based on the volcanoes covering its single, planet-wide continent. The toxic ash spewed by these volcanoes feeds the dense, black-grey jungles covering its plains and valleys.
The jungles are resistant to the most enthusiastic attempts to burn or defoliate them, and provide the perfect environment for the Kroot to fight a fluid war against the Imperium based on ambush and misdirection.
Ravacene chews through Astra Militarum regiments at an appalling rate. Only Death World veteran regiments can expect to last more than a few solar weeks before being withdrawn.
Worst of all is the psychological effect of fighting through its dense jungles, expecting Kroot ambushers behind every tree or fending off the illnesses that result from the ash-choked toxic atmosphere. Even with respirators and chem-suits, every Imperial soldier eventually suffers from the corrosive and poisonous air.
The Astra Militarum's objectives on Ravacene are simple. Ravacene is ideally placed to act as a staging post for a push into T'au space in the Reach, and its several moonlets would make ideal orbital dockyards for the voidships of the Imperial Navy. Before the planet can be used in this way, the Kroot presence on its surface must be exterminated.
The dense jungles mean this task must be carried out on the ground, one Kroot at a time, no matter how many Guardsmen it takes. For their part, the Kroot have evolved during their time on the world to match the ash jungles of Ravacene through the use of their ability to alter their genomes by ingesting other species' DNA.
- Deathwatch: Core Rulebook (RPG), pg. 356