Chapter 43: The Hidden Path of Sub-Floor Zero

The stairs leading to the lower archives were not meant for human feet. They were steep, narrow, and covered in a thick layer of slippery, glowing moss that fed on the residual mana leaking from the floors above. As Arthur led the way, the heavy rucksack on his back felt like a living thing, trying to pull him down into the darkness. Behind him, the clanking of Kael’s silver armor and the soft chanting of Sarah’s light spell were the only sounds in the oppressive silence.

"This place is a tomb," Jax whispered, his hand hovering over the hilt of his twin daggers. The scout’s eyes darted around the shadows, his senses tuned for the slightest movement. "I’ve been a Gold-Rank climber for five years, and I’ve never heard of anyone coming down here. There are no rewards in the basement, only death."

"That’s because you’ve been following the script," Arthur said without looking back. He stopped at a massive, rusted iron grate that was partially submerged in black, stagnant water. "The Tower rewards those who climb, but it hides its true secrets from those who follow the marked path. Sub-Floor Zero isn’t a tomb, Jax. It’s the recycling bin."

Kael stepped forward, his glowing broadsword illuminating the grate. "And how exactly are we supposed to get through this? It’s reinforced with ancient mana-locks. Even a High-Mage would need hours to break them."

Arthur didn’t answer. He knelt by the edge of the grate, his fingers tracing the cold, rusted metal until he found a small, circular indentation hidden beneath a patch of moss. It wasn’t a lock; it was a pressure sensor, a leftover from the Tower’s original construction phase.

"Sarah, give me a spark of pure mana," Arthur commanded. "Not a spell. Just raw, unrefined energy. Point it right here."

Sarah hesitated, looking at Kael for approval. The captain nodded grimly. She pointed her staff at the indentation, and a small, flickering blue spark jumped from the crystal tip.

The moment the mana touched the sensor, the heavy iron grate groaned. The sound was like a giant grinding its teeth. Slowly, the massive structure began to slide upward, revealing a dark, flooded tunnel that smelled of ozone and ancient decay.

"Welcome to the Hidden Path," Arthur said, standing up. "Keep your light low. The things down here don’t have eyes, but they can feel the heat of your magic."

They stepped into the tunnel, the freezing water reaching their knees. As they moved deeper, the walls began to change. They were no longer made of stone, but of a strange, translucent material that pulsed with a rhythmic, purple light. Inside the walls, Arthur could see the silhouettes of failed experiments—monsters that were too powerful or too unstable to be placed on the upper floors.

"What are those?" one of the twin warriors, a man named Bran, asked, his voice trembling.

"Prototypes," Arthur replied. "The things the Tower decided were too dangerous for the climbers to handle. As long as we stay on the path, they stay in the walls. Don’t touch the glass."

They walked for twenty minutes in tense silence until the tunnel opened into a vast, circular chamber. In the center of the room, floating above a pool of liquid mana, was a single, jagged shard of obsidian. It didn’t glow, but it seemed to vibrate with a frequency that made Arthur’s teeth ache.

"The Hidden Piece," Arthur whispered, his eyes widening.

"It looks like a piece of trash," Jax snorted, though he didn’t move closer. "What does it do? Give us a buff? A new skill?"

"It’s better than a skill," Arthur said, stepping toward the floating shard. "It’s a key. A ’Master Key’ for the 10th Floor’s logic. With this, we don’t just bypass the anomaly. We control it."

But as Arthur reached out his hand, the liquid mana beneath the shard began to churn. A massive, formless shape rose from the pool—a Void Slime, a creature that existed only to consume the mana of anything that entered its domain. It was translucent, filled with the half-digested remains of weapons and armor from climbers who had stumbled into the basement a century ago.

"Target identified," the Void Slime gurgled, a sound that shouldn’t have been possible.

"Get back!" Kael roared, stepping in front of Arthur and raising his shield. "Sarah, fire spell! Jax, find a weakness!"

"Wait!" Arthur shouted, but it was too late.

Sarah unleashed a massive fireball that struck the slime’s center. Instead of exploding, the fire was instantly absorbed, the slime glowing a brilliant, angry red as it doubled in size. The creature lunged, its gelatinous body slamming into Kael’s shield and sending the Gold-Rank captain flying across the room.

"It feeds on magic!" Arthur yelled over the roar of the creature. "Stop using spells! Physical attacks only!"

Jax and the twins lunged forward, their blades carving into the slime’s surface, but the wounds closed as quickly as they were made. The creature was too large, too resilient. It was a monster that was never meant to be fought by a standard party.

Arthur looked at the obsidian shard, then at the struggling adventurers. He didn’t have his Architect powers, but he knew the slime’s internal logic. It wasn’t a biological entity; it was a living mana-filter.

"Kael! Throw me your whetstone!" Arthur commanded.

"What? Why?" Kael gasped, struggling to stand as the slime’s acidic body began to melt his armor.

"Just do it!"

Kael reached into his belt and threw the heavy, gray stone. Arthur caught it in mid-air and immediately slammed it into the floating obsidian shard.

The impact didn’t break the shard. Instead, it caused a massive, high-frequency resonance. The obsidian began to scream, a sound so loud that the adventurers had to drop their weapons and cover their ears.

The Void Slime froze. Its translucent body began to vibrate violently, the mana inside it reaching a critical instability. A second later, the creature exploded into a thousand harmless droplets of clear water, leaving the obsidian shard hovering peacefully in the center of the room.

The chamber fell silent. Kael, Sarah, and the others looked at the weak, F-Rank porter who was now holding the obsidian shard in his hand. He wasn’t even breathing hard.

"How... how did you know that would work?" Sarah asked, her voice filled with a new kind of awe.

Arthur looked at the shard, then at his own reflection in the water. He saw a weak boy, but behind the eyes, the Architect was smiling.

"Because," Arthur said, his voice cold and certain. "I’m the one who wrote the instructions for the garbage disposal. Now, let’s go. The 11th Floor is waiting, and we’re already behind schedule."

He turned and headed toward a hidden door at the back of the chamber, leaving the Gold-Rank party to scramble after him. They were no longer the leaders of this raid. They were just the muscle for a man who knew the Tower better than the Tower knew itself.