The steam cloud swallowed us whole.

  One second, we were charging across the black snow of the foundry yard; the next, the world was completely white. It wasn't a fog. It was a physical wall of superheated vapor. The external temperature gauge on the dashboard spiked from freezing to eighty degrees Celsius in three seconds. The Centurion’s armored hull groaned as the sudden thermal shock caused the metal to expand.

  "Blind!" Rax shouted, slapping the useless radar screen. "Thermal is flooded. Optics are zero. We're flying in a milk bottle!"

  "Hold on," I said, my voice tight. I reached over and killed all the external sensors. They were just distractions now. I closed my eyes and gripped the primary control sticks. I didn't need to see. I needed to feel.

  Through the steel levers, through the hydraulic lines, through the massive feet planted on the concrete, I felt the vibrations of the Grand Foundry. Thump. Thump. Thump. A massive stamping press, three hundred meters to the left. Hiss-rattle. A high-pressure pipeline, running directly above us.

  "Trust the machine," I whispered, easing the throttle forward. The Centurion moved through the blinding white steam like a leviathan navigating the deep ocean. I steered us by the echoes of the factory's own heartbeat, threading the fifty-ton mech between massive load-bearing pillars that we couldn't even see.

  We cleared the primary cooling zone. The steam thinned slightly, turning from opaque white to a thick, greasy grey haze. We were in a wide transit corridor.

  "Contact!" Rax yelled.

  A patrol emerged from the haze, twenty meters ahead. It wasn't a pack of mechanical wolves. It was a squad of Imperial Guards, led by a junior mage in a crimson robe. They were escorting a line of chained slaves toward the processing vats.

  The mage stopped, his eyes going wide as the Centurion broke through the steam. Covered in mud, leaking swamp water, and vibrating with the terrifying, low-pitched whine of the V8 engine, we looked like a demon dragged straight out of the underworld.

  But the mage was an Imperial. He had been taught that magic was the ultimate power, and that machines were just crude toys for the unblessed. His shock morphed into arrogant sneer. He didn't order a retreat. He raised his staff. "Scrap metal!" he screamed, his voice cracking. "Burn!"

  He unleashed a Fireball. It was a textbook spell, perfectly formed, roaring through the air with the heat of a furnace. It hit the Centurion dead center on the chest plate.

  FWOOSH. Flames engulfed the cockpit glass.

  For a fraction of a second, the mage smiled. Then, the Centurion stepped out of the fire.

  The mithril plating didn't even glow. The sapphire crystals in the engine bay pulsed, easily absorbing the kinetic shock. I didn't reach for the weapon controls. I didn't say a word over the external speakers. I didn't afford him the dignity of a duel. I just pushed the throttle to 40%.

  The Centurion surged forward. The mage's smile vanished. He tried to cast a shield, holding up his hands as fifty tons of steel bore down on him. The magical barrier flared blue for a microsecond before the Centurion’s right foot shattered it like brittle glass. The foot continued its arc. CRUNCH.

  We didn't slow down. We marched right over the squad, the heavy metal feet leaving deep, bloody craters in the concrete. We didn't stop to look back. Physics didn't care about his pedigree.

  "Left turn ahead," I said coldly, adjusting the steering. "We're approaching the core."

  The corridor opened up into a cavernous underground chamber. The Grand Caldera. It was a terrifying monument to industrial cruelty. The room was the size of a cathedral, illuminated by the hellish orange glow of molten slag. Thousands of half-starved slaves were chained to conveyor belts, shoveling glowing mana-ore into the mouth of a singular, massive machine in the center.

  It was a boiler. But it was the size of a five-story building.

  It was made of black iron, wrapped in thick chains, and glowing with an intense, internal heat.

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  "Look at the shielding," Amelia whispered, pointing to a shimmering, translucent dome that completely encased the boiler. "That's an Absolute Defense Barrier. Tier 4 abjuration. You could drop a mountain on it, and it wouldn't crack."

  Rax swung The Riveter around, taking aim at the center of the dome. "Let's test that theory. Load high-explosive."

  "No," I placed a hand on his arm, stopping him. "Amelia is right. An Absolute Defense Barrier is designed to absorb external kinetic and magical energy. If you shoot it, the shield will just convert the kinetic energy of the spike into more strength for the barrier."

  "So it's invincible?" Rax scowled.

  "Nothing is invincible," I said, my eyes scanning the massive structure. "You just have to understand what it's trying to do. It's a boiler. It heats water to create steam pressure to turn the foundry's turbines. Which means..."

  My eyes locked onto the top of the boiler, where a massive, two-meter-wide steel pipe protruded through a specific opening in the magical dome, venting excess steam toward the ceiling.

  "...it must have an exhaust," I finished. "A pressure release valve. If it doesn't vent, the pressure builds infinitely."

  I looked at Rax, a cold, calculating grin spreading under my mask. "We don't need to break the shield to destroy the boiler. We just need to stop it from breathing. We let the shield become the bomb casing."

  "Oh, you brilliant, twisted bastard," Rax laughed.

  "Amelia," I turned to her. "I'm going to seal that vent. The moment I do, this entire chamber is going to turn into a pressure cooker. I need you to clear the floor. Get those slaves out of the blast radius."

  Amelia didn't hesitate. She unbuckled her harness and stood up, popping the top hatch of the Centurion. She climbed out onto the roof of the mech, the intense heat of the Caldera immediately whipping her hair around.

  I engaged the jump jets and pushed the throttle to maximum. The Centurion leaped from the viewing gantry, crashing onto the main floor. Slaves screamed and scattered as the giant metal beast landed among them.

  "Run!" Amelia's voice boomed, magically amplified by a wind spell, echoing off the cavern walls. She swept her hands forward. A massive gale of wind erupted from her palms, not to destroy, but to blow away the toxic fumes and the Imperial overseers who were trying to whip the slaves back into line. "The boiler is going to blow! Get to the transit tunnels! NOW!"

  The slaves didn't need to be told twice. Seeing their overseers thrown against the walls by hurricane-force winds, they dropped their shovels and surged toward the exits.

  "Hold on!" I shouted to Amelia.

  I steered the Centurion straight toward the massive boiler. The heat radiating from the Absolute Defense Barrier was blistering. The warning alarms in the cockpit screamed: CRITICAL TEMPERATURE.

  We reached the base of the structure. I didn't try to punch the shield. I manipulated the hydraulic controls for the arms. We didn't have hands, but the left arm was capped with a massive, flat hydraulic ram we usually used for bracing.

  I raised the left arm, aiming for the massive exhaust pipe protruding just above the magical dome. "Closing the valve," I gritted my teeth.

  I slammed the hydraulic ram into the side of the steel exhaust pipe. CLANG. The pipe dented.

  I backed the arm up and slammed it again. SCREEECH. The two-meter-wide pipe buckled, folding inward on itself.

  Steam immediately began to shriek, forcing its way through the narrowing gap. The sound was deafening, like a thousand kettles boiling over simultaneously.

  "Seal it!" Rax yelled over the noise.

  I engaged the plasma cutter on the right arm. I drove the blade of blue fire into the folded metal, melting it, welding the crumpled steel together into a solid, airtight plug.

  The shrieking stopped. An eerie, terrifying silence fell over the immediate area, broken only by the deep, subterranean rumble of the boiler.

  I looked at the massive analog pressure gauge mounted on the side of the machine. The needle, normally resting in the green zone, was suddenly moving. Fast. It swept through the yellow zone. It hit the red zone. It kept going, pinning itself against the maximum peg until the glass face cracked.

  RUMBLE. The floor under the Centurion shook violently.

  Inside the Absolute Defense Barrier, the boiler began to swell. Literally swell. The black iron groaned, bulging outward as the millions of pounds of steam pressure, denied their exit, sought a way to escape. But they couldn't break the iron. And the iron couldn't expand further because it hit the magical shield.

  The magical runes on the barrier began to flash frantically, turning from blue to a panicked, glaring red. The shield was trying to contain the force, but it was designed to stop attacks from the outside, not an infinitely expanding thermodynamic nightmare from the inside.

  Up on the gantry, the senior Imperial Mages finally realized what was happening. They abandoned their posts, screaming in terror, scrambling over each other to reach the blast doors. They were kicking and screaming, desperate to escape the inevitable consequence of their own arrogance.

  "Amelia, get back in!" I roared, reversing the Centurion's gears.

  She dropped back through the hatch, sealing it tight. "They're clear! Most of the slaves made it into the tunnels!" she gasped.

  "We need to be anywhere but here," I said, slamming the throttle into high gear.

  We sprinted back toward the drainage tunnels we had entered from. Behind us, the sound of tearing metal reached a crescendo. The Absolute Defense Barrier flickered, unable to compute the thermodynamic impossibility it was trying to contain.

  CRACK. A single, blindingly bright fault line appeared across the magical dome.

  "Brace for shockwave!" I yelled, driving the Centurion headfirst into the dark, reinforced concrete of the drainage pipe.

  Then, the Grand Caldera detonated.