The sound of mining had changed. It was no longer the dull thud of stone against dirt, nor the desperate scraping of a dying man. It was a rhythmic, resonant crack that echoed through the spiral tunnel.
Boom. Crack. Rumble.
Ji Han stood before the granite face at the bottom of the shaft, now thirty meters deep. He breathed in—a slow, controlled inhale that pulled the heavy, humid air into his lungs. He circulated the Qi through his meridians, feeling the hum of power in his blood.
He didn't have a pickaxe. He held a shard of granite, shaped like a crude chisel, in his left hand. In his right hand, he held a heavy, rounded river stone he had unearthed earlier.
"Condense," he whispered.
A faint, white aura flickered around his right hand. It wasn't fire; it was pressure made visible.
He struck.
CRACK.
The chisel drove into the bedrock, splitting a section of stone the size of a torso. Ji Han grabbed the heavy rock as it fell, tossing it onto a pile behind him with casual ease. His Strength had scaled with his cultivation. A fifty-kilogram rock felt like a bag of groceries.
"Efficiency: 400% increase," Ji Han noted, wiping stone dust from his face.
Behind him, Lin Qinghe was sorting the debris. She was no longer the invalid she had been three months ago. The constant intake of spirit-roots and the cool underground environment had allowed her to walk and perform light labor. She was stacking the shattered granite to reinforce the tunnel walls, creating a sturdy archway.
"The resonance is changing," Lin Qinghe said, pausing with a rock in her hand. She tilted her head, her ear pressed toward the tunnel floor.
Ji Han stopped. He closed his eyes, extending his newfound Perception.
He felt the vibration of the earth. Usually, it was a solid, dense feedback. But now...
Thrum... thrum...
There was a hollowness. A slight echo to his movements.
"Cavity," Ji Han diagnosed. "Below us."
"Be careful," Lin Qinghe warned, her voice low. "Underground cavities accumulate Yin Qi. The surface is a Yang hellscape. The depths will be a Yin freezer. The thermal shock can stop your heart."
Ji Han nodded. He swapped his stone hammer for the rusty iron sword. It was practically a crowbar now, chipped and bent, but it was still metal.
He knelt by the crack in the floor. He channeled his Qi into the blade.
"Open."
He drove the sword into the fissure and twisted.
With a grinding screech, the floor gave way. A section of rock collapsed inward, tumbling into darkness.
A blast of air shot up from the hole.
It wasn't just cool. It was arctic.
Ji Han recoiled, gasping as the freezing air hit his sweat-soaked skin. It felt like opening a freezer in the middle of a sauna. Frost instantly formed on the edges of the hole.
"Yin Qi," Lin Qinghe confirmed, shivering as she pulled her tattered robes tighter. "Pure and heavy."
Ji Han crawled to the edge and looked down. He grabbed the moss-light stone and dropped it into the hole.
It fell for two seconds.
Splash.
The sound was music.
"Water," Ji Han breathed. "Real, standing water."
He didn't wait. He grabbed the rope they had woven from braided grass fibers—dried and brittle, but doubled up for strength—and secured it to a granite pillar.
"I'm going down," Ji Han said.
"Do not touch the water directly," Lin Qinghe ordered. "If the Yin Qi is too strong, it will freeze your blood. Test it first."
Ji Han nodded and rappelled down. The drop was about five meters.
He landed on a slippery, rocky ledge. The air here was biting cold, a stark contrast to the oven thirty meters above. He picked up the moss-stone.
He was in a natural limestone cavern, roughly the size of a small gymnasium. Stalactites hung from the ceiling like jagged teeth.
And in the center of the cavern lay a pool.
It was black, still, and glass-smooth. It was about ten meters across. The moss-light reflected off the surface, revealing no ripples.
Ji Han approached it cautiously. The temperature dropped with every step. He could see his breath puffing out in white clouds.
He reached the edge. He didn't touch the water. He held his hand an inch above it.
The cold radiated off the surface like heat off a stove.
"System scan?" he muttered. No response. The System didn't identify natural features unless he interacted with them.
He drew his sword and dipped the tip into the black water.
Hiss.
Ice instantly began to creep up the metal blade, spreading like white mold. Ji Han yanked the sword back. The tip was encased in a crystal of blue ice.
"Supercooled," Ji Han realized. "It's liquid, but barely."
He looked around the cavern. The walls glittered. He moved the light closer.
Embedded in the limestone were veins of a dark, metallic ore. It wasn't gold or iron. It absorbed the light rather than reflecting it.
"Spirit Ore," a voice echoed from above. Lin Qinghe was peering down the hole. "Black Iron. Excellent for conducting Qi. Terrible for holding an edge, unless refined."
Ji Han looked from the deadly water to the valuable ore.
"We have a refrigerator," Ji Han called up. "And a mine."
He sat down on the cold rock, shivering uncontrollably, but smiling. The Zenith sun could burn the world to ash above them. Down here, wrapped in the embrace of the earth, he had found the perfect counter-balance.
But then, a sound broke the silence.
Scritch. Scritch.
It came from the darkness beyond the pool, where the cavern narrowed into a smaller tunnel.
Ji Han froze. He doused the moss-light, plunging the cavern into pitch blackness.
His Perception screamed a warning. Something was moving. Something with too many legs.
He gripped his frozen sword. The Novice Barrier protected the 1km circle from the outside. But this cavern was under his territory.
If something lived down here, it was technically his roommate.
And roommates didn't always get along.