The Archmage Became A Mushroom Tamer

Chapter 6

Chapter 6 · 1,451 words

## Ch006 - Fireball Mushroom Mk I

The crawlspace smelled of rust and old water.

Aldric sat cross-legged on the concrete floor, his knees drawn up because the ceiling was too low to sit any other way. The access panel (a square of warped plywood behind the F-tier dormitory's east wall) had taken him twenty minutes to pry open. What he'd found behind it was barely a meter tall, threaded with pipes that hadn't carried anything useful in decades, and warm.

That warmth was the point.

The academy's primary mana conduits ran beneath the oldest buildings, and the F-tier dormitory was the oldest building on campus. The conduits leaked residual thermal energy through their casings, a defect that the maintenance staff had long since stopped repairing. The crawlspace sat directly above a junction where three conduits met. Ambient temperature: roughly thirty degrees Celsius. Humidity: high. The air tasted of mineral deposits and something faintly organic, like the breath of a compost heap.

It was, in every measurable sense, a terrible workspace.

It was also completely invisible to anyone who wasn't looking for it, and it was warmer than any cultivation chamber Aldric had access to. Three centuries of experience had taught him that the best laboratories were the ones nobody else wanted.

He'd been back here for six hours.

The incineration of his drainage pipe culture was fourteen hours behind him. He had not spent those hours grieving. Grief was a luxury for people who hadn't just been handed a probation deadline and a blank slate. Instead, he had spent the first eight hours mapping the crawlspace: its dimensions, its pipe routes, the direction of residual mana bleed from the conduits below. The next two hours he'd spent behind the greenhouse, at the discarded-materials bin.

The bin was a metal cage bolted to the exterior wall of the greenhouse district, open to weather and neglect. Inside it, the academy's cultivation program threw away anything that had failed to meet its exacting standards: cracked pots with residual mycelium, substrate batches that had been contaminated by ambient spores, dead mushroom cultures whose spore prints no longer matched the registry.

Aldric saw a starting inventory.

He'd selected three items. The first was a cracked ceramic jar, a hairline fracture running from rim to base, but the clay itself was high-fired and dense. Its thermal retention properties were adequate. Not excellent. Adequate. The second was a bag of contaminated substrate, the kind that had been flagged for foreign spore incursion. Aldric had smelled it through the bag and identified the contaminant as a common ambient mold, harmless, easily sterilized with a careful mana pulse. The substrate beneath was still nutrient-rich. The third item was a dead Luminescent Cap culture, its mycelium long since ceased producing light. The culture was dead. The spores were not.

Luminescent Cap mycelium had an unusual property: its cellular structure was an excellent thermal conductor. The mushroom used it to distribute metabolic heat evenly across its fruiting body. Bioluminescence was a byproduct of thermal distribution. Dead or alive, that cellular architecture persisted. It was the best thermal scaffold Aldric could find in a garbage bin.

He arranged his materials on the crawlspace floor.

The cultivation itself was straightforward in concept and agonizing in execution. He needed the Luminescent Cap mycelium to develop thermal storage vacuoles, microscopic pockets within the cellular structure that could absorb and retain heat energy. In his old world, he would have used a temperature-controlled cultivation chamber with mana-regulated heating elements. Here, he had two things: the ambient warmth of the mana conduit junction, and his own mana, channelled through his fingers in pulses so small they would have been imperceptible to any monitoring instrument.

The technique was borrowed from third-year thermal spell theory. Alternate hot and cold stimuli. Force the organism to adapt by developing storage capacity. It was the same principle that produced thermal-resistant golem cores. Except instead of mineral substrate, he was working with living fungal tissue, and instead of a regulated kiln, he was using his own body as the mana source.

He pressed his fingertips to the cracked ceramic jar, which he'd filled with the sterilized substrate and inoculated with Luminescent Cap spores. He sent a pulse of mana through the clay. Warm, not hot. A fraction of a degree above ambient. Then he waited. Counted to forty. Then a cold pulse, drawing heat away, dropping the substrate temperature by the same fraction. Then waited again.

The mycelium, caught between warmth and cold, did what all living things did when subjected to selective pressure: it adapted.

He couldn't see the changes happening. Not yet. But he could feel them through the faintest resistance patterns in the substrate. The mycelium developed denser cell walls, creating vacuoles that trapped thermal energy. Each pulse cycle took ninety seconds. He needed hundreds of cycles. His mana, already shallow in this wretched body, thinned to a trickle after the first hour. His hands began to shake.

He kept going.

The crawlspace narrowed around him. The pipes overhead dripped at irregular intervals. Once, he had to pause and redirect a droplet that was falling too close to the jar. Excess moisture would drown the developing mycelium before the thermal adaptation took hold. He used a splinter of wood to channel the drip toward a lower pipe. Crude. Effective.

Three hours in, the mycelium began to glow.

Not bioluminescence. Not yet. The faintest orange tint at the surface of the substrate, visible only in the crawlspace's near-total darkness. Thermal radiation. The mycelium was storing heat and releasing it slowly, the way a stone pulled from a fireplace radiates warmth long after the flame has died.

Aldric stopped counting pulses. He held his hands against the jar and felt the warmth. It came from within the substrate itself, not from the conduits below. The mycelium had done it. Thermal storage vacuoles, developed through selective pressure applied by a man who had once designed siege spells that could melt castle walls.

He allowed himself to sit back. His shoulders hit the ceiling. He didn't mind.

"Fireball One," he said, to the jar, to the mycelium, to the orange glow that was the first sign of life he'd coaxed from this world's substrate. "Your thermal output is currently insufficient. We will need to discuss your performance expectations."

The mushroom did not respond. It continued to glow, faintly, like an ember that had decided to keep burning after the fire was supposed to have gone out.

Aldric reached up to adjust his glasses. His fingers met bare skin. He stopped, let his hand drop, then caught himself doing it again. The phantom weight on the bridge of his nose, the habitual gesture of a man who had worn spectacles for two hundred and seventy years before his body had been remade without them.

He lowered his hand.

The new body remembered things the old mind had to relearn. The fingers that had once traced complex spell formations now trembled from mana exhaustion.

He was thirty-seven years old in the body of an eighteen-year-old. His hands shook. His mana reserves were a fraction of what they had once been. He was sitting in a crawlspace behind a dormitory wall, talking to a mushroom in a cracked jar.

Fireball Mushroom Mk I was alive. Its thermal discharge was a proof of concept. It demonstrated that the principles worked, that three centuries of magical theory could be applied to this world's fungal biology, that the gap between knowledge and resources could be bridged by patience and selective pressure.

He needed phosphorus-rich bone meal to increase the energy density. He needed a heat-resistant substrate base to contain higher thermal loads. Neither was available in the discarded-materials bin behind the greenhouse.

His Substrate Analysis skill, the same skill the tutorial described as useful for identifying nutrients in mushroom soil, had identified one source for both: the academy's low-level secret realm. Freshman orientation trials. Phosphorus-rich bone fragments from skeleton-type mana beasts. Heat-resistant moss from the thermal vent regions.

Access was restricted. But the realm opened for maintenance every month, and the next maintenance window was in four days.

Aldric looked at the jar. The orange glow had faded to a dull warmth. Fireball One was resting, conserving the energy it had stored. It had done what he'd asked. By any objective measure, it was inadequate.

"Adequate," he told it. "For now."

He covered the jar with a scrap of cloth he'd torn from the lining of his dormitory's moth-eaten curtain, settled back against the crawlspace wall, and began to plan.