The sealing of the mountain had saved the souls of Ashfall from the "Breath of the King," but it had simultaneously sentenced them to a slow, nutritional erosion. Kael stood on the observation gantry of the Green Ring, watching the once-vibrant stalks of dwarf grain lean heavily in the artificial chill. The arc-lamps, though brilliant, could not compensate for the loss of the subtle atmospheric exchanges with the surface, and the Ice Shield's parasitic drain on the geothermal core had forced a reduction in the "Light-Cycle." At a population of one thousand, the calorie-math was failing. The mountain was consuming more than it could grow. To prevent the "Hunger-Crawl," Kael initiated the construction of the Protein Vat—a Tier 16 project that would move the barony's food production from the aesthetics of agriculture to the cold efficiency of industrial fermentation.
The technical core of the system was the Anaerobic Mycelium Reactor. Kael realized that light was an expensive luxury in a sealed mountain, but heat was a byproduct he had in abundance. He moved the production three tiers deeper, into the jagged basalt vaults of Tier 16, where the rock itself was warm to the touch. Here, he installed a series of massive, copper-lined fermentation tanks. Instead of sunlight and soil, these tanks utilized a "Nutrient-Broth" derived from the Digester's processed waste and the cellulose-rich husks of the failing Green Ring crops. Within this broth, Kael introduced a hardy, engineered strain of deep-cave fungal culture—a white, rubbery mycelium that could double its mass every six hours as long as the temperature remained a constant ninety-eight degrees.
"We are moving past the sun, Elms," Kael said, the air in Tier 16 thick with the heavy, yeasty scent of fermentation. It was a smell like rising bread, but sharper, more primal. "A thousand people cannot live on the whims of a grain stalk that needs a summer it will never see. We are going to grow 'Meat-Stone.' It won't have the texture of a harvest, but it will have the protein of a legion's ration. We are turning our waste directly into muscle."
The grit of the construction was a descent into a subterranean steam-bath. The Tier 0 laborers and the Aspirant engineers worked in the "Hot-Zones" of Tier 16, their skin slick with sweat and blackened by the basalt dust. They had to install the "Heat-Exchange Coils"—miles of copper tubing that spiraled through the vats, carrying the secondary steam from the geothermal bore to keep the mycelium at its peak growth rate. The workers moved in four-hour shifts, their lungs struggling with the high humidity and the lack of moving air. In the dark, the only light came from the dim, red glow of the pressure-gauges and the occasional spark from a smith's hammer as they bolted the copper lids into place.
Socially, the Protein Vat represented a profound "Dietary Devaluation." When the first batches of the fungal paste—a dense, pale-grey substance with the consistency of thick curd—were distributed in the communal halls, the reaction was one of grim necessity. The "Northern Refugees," who still remembered the taste of surface-grown fruit and fresh grain, looked at the "Vat-Pulp" with a mixture of revulsion and despair. The "Sanitary Corps" had to work alongside the "Green-Keepers" to process the pulp, mixing it with dried herbs from the fading Green Ring and a heavy dose of mineral salts to make it palatable. It was the "Grit of Survival" in its most literal form: the taste of a society that had sacrificed its palate for its pulse.
A technical failure occurred during the first massive "Harvest-Cycle." The primary agitator in Vat-4—a giant iron paddle designed to keep the mycelium from settling and suffocating—seized due to a build-up of calcified minerals from the "Living Water." Within minutes, the dense fungal mass began to "Go Sour." Without agitation, the center of the vat began to ferment anaerobically, producing a pocket of pressurized methane and hydrogen-sulfide. The copper lid began to groan under the internal pressure, the rivets straining like the buttons on a bursting tunic.
Kael utilized the "Centrifugal-Shear" bypass. He didn't try to fix the paddle while the vat was pressurized. Instead, he opened the "Flash-Drain" at the base of the tank, using the high-pressure steam-line to blow the entire four-ton mass of sour mycelium into the "Digester" sumps. It was a loss of nearly ten thousand calories, but it prevented a catastrophic "Vat-Burst" that would have flooded the tier with toxic gas and boiling sludge. To prevent a recurrence, he redesigned the agitators with "Graphite-Sleeves"—self-lubricating bearings that could withstand the mineral-rich environment of the protein broth.
The engineering of the Protein Vat successfully decoupled Ashfall from the limitations of light. Within a month, the Tier 16 reactors were producing enough protein to sustain a population of fifteen hundred, creating a "Nutritional Surplus" for the first time since the blockade began. The yellowing grain in the Green Ring was no longer a death sentence; it was repurposed as a carbon-source for the vats. The mountain had solved its hunger, but at the cost of its last remaining sensory connection to the natural world.
The population count remained steady at 1,000, but the "Golden Finger" warning in Kael's head was beginning to thrum with a new frequency. It wasn't the heat of the fire or the vibration of the bore. It was a "Cold-Static"—a sensation of being watched from a direction that didn't exist on his maps.
"The Empire has stopped pounding the roof, Elms," Kael said, standing in the quiet of the Logic Vault, his eyes fixed on the Seismic Mirror. The sky-ships were still there, but they were no longer dropping bombs. They were dropping "Sondes"—small, weighted iron spheres that didn't explode, but instead "Sank" into the marsh-silt around the mountain. "They aren't trying to break the stone anymore. They're trying to 'Map the Magnetic Field.' Vane is looking for the geothermal bore's electrical signature. He's looking for the 'Heart' of the mountain so he can hit it with a 'Lightning-Strike'."
Kael began sketching the Faraday-Shroud—a project to wrap the entire geothermal bore and the Galvanic Line in a mesh of copper and lead, turning the mountain into a "Magnetic Ghost" that would be invisible to the Empire's new detection tools.