Arthur stared at the glowing blue screen hovering in the dark alley.
His heartbeat quickened—just slightly.
The system hadn't simply removed the corruption.
It had consumed it... refined it... and fused it into something far more dangerous.
[Skill Mutation Complete!]
[New Skill Acquired: Summon Plague-Bone Assassin (Lv.1)]
[Tier: Rare (Growth-Type)]
[Cost: 15 Mana]
[Effect: Summons a highly agile skeletal assassin forged from crystallized venom. Its strikes inflict [Lethal Corrosion], ignoring basic physical defense and melting armor.]
[Bonus Passive: 100% Immunity to low-to-mid tier poisons and toxins.]
Arthur read it once.
Then again.
Growth-Type.
A skill that evolves... and breaks the limits of its tier.
A faint smile appeared on his lips.
"Perfect."
He closed the interface.
He had a Level 10 tank.
Now, he had a lethal assassin.
Arthur exhaled slowly.
"I'm no longer just an F-Rank Necromancer…"
His pitch-black eyes darkened.
"I'm a one-man guild."
He needed to test it.
And more importantly—
He needed to grow stronger. Fast.
The Academy's Graduation Dungeon Exam was only a week away.
Level 3... wasn't enough.
Arthur tightened his cloak and moved deeper into the Underground Sector.
Not the graveyard. Too exposed.
Instead—
The Slum Sewers.
A labyrinth of rot and darkness. Recommended for Level 5–10 parties.
...
Twenty minutes later.
The air was thick. Damp. Rotten.
Faint green moss glowed along cracked stone walls.
Squeak... scratch...
Red eyes flickered in the darkness ahead.
Not one.
Not two.
Six.
Mutated Dire-Rats. Level 6.
Large as dogs. Fast. Vicious.
They smelled him.
And lunged.
Arthur didn't move.
"Arise."
[Mana: -15]
A magic circle flared beneath him—
not gray... but toxic neon green.
Something emerged.
Not a fragile skeleton.
A predator.
Slim. Black bones threaded with glowing green veins.
Two reverse-grip bone daggers dripping acid.
Its posture low... like a hunter ready to kill.
But it didn't look at the rats.
The Plague-Bone Assassin slowly turned its skull toward Arthur.
The green fire in its hollow eyes flickered violently. It didn't kneel. It didn't obey the immediate combat directive of the System.
It raised one of its acid-dripping daggers, pointing the jagged tip directly at Arthur's chest.
A cold chill ran down Arthur's spine.
It's evaluating me, Arthur realized, his mind racing. The corruption wasn't just purified... it gave the skill a fractured sentience.
"...Hungry..." a raspy, disembodied hiss scraped against the inside of Arthur's skull.
The anomaly wasn't a loyal soldier. It was a starving addict, and it demanded to be fed.
Arthur didn't step back. He didn't drop his gaze.
He forced his monstrous, unyielding Mental Energy downward, pushing the absolute, crushing weight of the [Calamity Seed] directly onto the rebellious summon.
"Then eat," Arthur commanded, his voice cold and absolute, pointing a pale finger toward the charging horde of Mutated Dire-Rats.
"Slaughter."
The Assassin's skull snapped back toward the monsters.
It vanished.
Not ran—vanished.
A blur of green.
It reappeared behind the first rat.
Slash.
The throat split—
HSSSSSS—
The body melted instantly into bubbling green sludge.
The others froze.
Too late.
The Assassin moved again—faster.
Slash. Pierce. Decapitate.
But the rats were Level 6 Mutants. They weren't mindless slimes.
One rat broke through the slaughter, using the dissolving corpse of its pack-mate as a shield, and rushed directly toward Arthur, fangs wide.
It lunged, snapping its jaws shut around Arthur's forearm.
For a fraction of a second, the razor-sharp teeth pierced his coat.
But there was no pain. No blood.
The moment the rat's saliva touched Arthur's skin, the beast shrieked in agony.
[Passive Skill Activated: 100% Poison Immunity]
The corrosive venom coating the rat's fangs was completely nullified, but the rat itself wasn't immune to the raw, toxic domain-mana leaking from Arthur's pores. The beast's jaw began to aggressively rot away.
Before Arthur could shake it off, the Assassin appeared mid-air.
Slice.
The rat split cleanly in half, its dissolving body hitting the wet stone.
Five seconds.
Six monsters... gone.
Only sizzling acid remained on the floor.
But the Assassin didn't immediately return to the shadows.
It stood over the melted corpses, its hollow eyes slowly turning back to Arthur.
It lingered for a fraction of a second too long. A silent, terrifying promise that if Arthur ever showed weakness, he would be the next meal.
Arthur stared at the dissolving remains, feeling a sudden, unnatural rush of euphoria flooding his veins. A twisted, dark satisfaction that didn't belong to him.
[Notice: Empathy Suppression Active. Corruption Level: 3%.]
It shares the high of the kill with me, Arthur realized, his breath hitching as he aggressively buried the addictive rush. It's trying to make me like it.
A weapon like this...
In the wrong hands—
Would be a disaster.
A faint, chilling smile touched his lips.
"Good thing it's mine," Arthur murmured quietly.
He paused, his pitch-black eyes locking onto the Assassin as it finally melted back into his shadow.
"...As long as it stays that way."
He ordered the Assassin to collect the mana cores.
The shadow shifted, pushing the small, glowing orbs toward him. But then, the shadow stopped.
Slowly... it stretched, pointing a jagged, two-dimensional finger toward a collapsed wall deeper in the tunnel.
Arthur frowned.
He stepped forward, pushing aside broken bricks with his boot.
Then—
He saw it.
A faint purple glow... pulsing steadily behind the rubble.
His breath slowed.
He cleared the debris completely.
A swirling, dark-purple portal revealed itself.
The air around it hissed.
Toxic mist leaked from the gate... aggressively corroding the surrounding stone.
[Ding!]
[Anomaly Detected.]
[Hidden Dungeon Found: The Forgotten Toxic Catacombs]
[Recommended Level: 15–20]
[Warning: Extreme toxicity detected. Entry highly discouraged.]
A Hidden Dungeon.
Untouched.
Unclaimed.
Full of loot... and death.
Arthur's gaze sharpened.
Level 20.
For anyone else—certain death.
A full party would hesitate.
Even instructors would prepare carefully.
But Arthur wasn't "anyone else."
His eyes shifted to his passive skill.
[100% Poison Immunity]
He looked back at the gate.
As he stepped closer, the dark-purple vortex didn't just swirl. It reacted.
The swirling mist slowed down, parting slightly in the center, almost as if the dungeon itself was inviting him in. Recognizing a kindred spirit in the corruption he carried.
Toxic. Lethal. Forbidden.
A slow grin spread across his face.
"Discouraged?" he muttered.
He stepped forward.
"Then it's mine."
And without hesitation—
Arthur walked into the darkness.