The dungeon stood where the land broke.
A jagged scar in the earth, ringed by fractured stone and warning pylons etched with dull mana runes. The air around it felt heavier—not oppressive, but stagnant, like water that hadn't moved in too long.
Eren stopped a few meters away.
This was an F-rank dungeon.
The lowest classification.
In the public registry, F-rank dungeons were considered training grounds—safe enough for beginners, profitable enough to justify maintenance, dangerous enough to cull the careless.
In Ashen Crown , dungeons were categorized by origin and behavior:
Natural-type — Formed from mana saturation over time
Corruption-type — Born from death, resentment, decay
Artificial-type — Created or altered by sentient beings
This one was a Natural-Type Growth Dungeon.
That meant:
Stable layout
Repeating monster ecology
Resource generation over time
Good for herbs.
Predictable monsters.
Bad for complacency.
Eren adjusted his pack and stepped forward.
Crossing the threshold felt like submerging into cold water.
The light dimmed instantly. Stone walls replaced open sky, carved not by tools but by pressure and time. Faint luminescent moss clung to cracks, providing just enough visibility to move without artificial light.
The dungeon breathed.
Not literally—but mana circulated here differently, flowing in slow loops rather than linear streams.
Eren moved carefully.
Sword drawn, not raised.
His Calm Mind settled immediately, filtering ambient noise. Every footstep was placed deliberately. Every breath measured.
F-rank dungeons housed low-tier monsters, but that didn't mean harmless.
The most common inhabitants of growth-type dungeons were:
Grave Rats — fast, swarm-based scavengers
Stone Crawlers — ambush predators with hardened shells
Mire Wolves — solitary hunters, low intelligence, high aggression
Eren encountered the first sign quickly.
Scraping.
Soft. Repetitive.
He stopped.
From the shadowed side tunnel ahead, something moved.
A Grave Rat emerged—large as a dog, fur matted with mana residue, eyes glowing faintly red. Its incisors scraped against stone as it sniffed the air.
Then another.
Then three more.
A pack.
Eren didn't retreat.
He shifted his stance.
The first rat lunged.
Eren stepped inside its movement, blade flashing upward in a short arc. The sword bit cleanly into its neck—no wasted motion. He twisted, pulling free as the body collapsed.
The second leapt immediately.
Eren kicked off the wall, avoiding its jaws, and brought the blade down diagonally. The rat screeched once before going still.
The remaining two hesitated.
That was their mistake.
Eren surged forward, closing distance before they could regroup. One slash. Then a thrust.
Silence returned.
He exhaled slowly.
No mana expenditure.
Clean execution.
He crouched and retrieved the monster cores—small, dull crystals embedded near the chest cavity. Low value. But sellable.
He stored them carefully.
Then moved on.
Herbs
Deeper in, the dungeon opened into a wider chamber.
Here, the mana density increased slightly.
Eren felt it immediately.
Along the walls grew pale-blue plants with translucent leaves—Mistroot.
Low-grade mana herbs.
When refined or consumed properly, they increased mana circulation efficiency over time. Not instant breakthroughs—but foundations.
Exactly what he needed.
Eren harvested carefully, using a small blade to avoid damaging the roots. He collected several bundles, wrapping them in treated cloth to preserve potency.
This alone made the trip worthwhile.
But he hadn't come only for herbs.
He moved deeper.
The Hidden Route
In the novel, this dungeon had been described as "exhausted."
Cleared countless times.
Nothing special.
Which was why no one noticed what lay beneath.
Eren reached a narrow corridor that ended in a collapsed wall.
At least, that's what it looked like.
He knelt.
Placed his palm against the stone.
The mana here was… wrong.
Not corrupted.
Not dense.
But absent.
A void where flow should exist.
"…There you are," he whispered.
Black Nox did not resonate with power.
It resonated with absence.
Eren planted one of the mana explosives carefully against a structural fault line—not enough to collapse the tunnel, just enough to disrupt surface integrity.
He retreated.
Triggered it.
The blast was contained, sharp, precise.
Dust filled the air—but when it cleared, a narrow opening revealed itself behind the false wall.
A hidden descent.
Unregistered.
Untouched.
Eren didn't enter yet.
Not today.
He marked the location mentally.
First—experience.
Second—resources.
Third—preparation.
Black Nox would not be claimed by impatience.
Final Encounter
As he turned to leave, the dungeon reacted.
A low growl echoed through the chamber.
Heavy.
Measured.
A Mire Wolf stepped into view.
Larger than expected.
Its fur was dark and slick, veins pulsing faintly with mana. Yellow eyes locked onto Eren with predatory focus.
This one was stronger than average.
Eren adjusted his grip.
The wolf charged.
Fast.
Eren rolled aside, barely avoiding snapping jaws. He slashed at its flank—metal screeching as the blade scraped reinforced hide.
The wolf recoiled, then struck again.
Eren ducked, thrusting upward. The blade pierced beneath the jaw, sinking deep. Mana surged instinctively—controlled, restrained.
The wolf convulsed, then fell.
Eren staggered back, breathing hard.
That… cost mana.
He waited until his breathing stabilized before approaching.
He retrieved the monster core—larger, clearer than the others.
Worth real coin.
He straightened slowly.
No injuries.
Minor mana drain.
Acceptable.
Exit
Eren retraced his steps and exited the dungeon without incident.
Sunlight greeted him like something unfamiliar.
He adjusted his pack.
Herbs secured.Cores collected.Hidden route confirmed.
He hadn't gained power.
Not yet.
But he had gained certainty.
The dungeon was not empty.
And Black Nox was real.