The Drowned Vault's entrance was a flooded elevator shaft in an abandoned parking garage.
Taeyang stood at the edge, looking down at black water that reflected no light. The dungeon's presence pulsed up from below — something vast and cold and patient.
C-rank, according to Ghost's data. Harder than the D-rank runs he'd been doing, easier than the B-ranks that had gotten him in trouble. The right difficulty for testing himself without the Association watching.
He'd prepared carefully. Waterproof equipment from the black market. Breathing potions that extended underwater tolerance. A [Water Resistance] skill gem he'd looted three runs ago, now slotted into his armor.
None of it would matter if the dungeon broke him. But at least he'd tried.
Taeyang jumped.
The water swallowed him.
---
The Drowned Vault was beautiful in the way drowning must be beautiful — serene surfaces above infinite darkness below.
The dungeon had formed inside an underwater treasury from some ancient civilization. Stone columns draped in kelp. Vaulted ceilings covered in bioluminescent coral. Golden treasures scattered across the floor, glinting with reflected light from creatures that shouldn't exist.
```
[C-RANK DUNGEON: The Drowned Vault]
[Environmental Hazard: Pressure (increases with depth)]
[Environmental Hazard: Oxygen drain (constant)]
[Monster Type: Drowned Guardians (slow but durable)]
[Boss: The Vault Keeper (pressure control, water manipulation)]
```
Pressure and oxygen. Two clocks ticking down simultaneously. Parties handled this through rotation — some members diving deep while others recovered above, trading off until the dungeon was cleared.
Solo meant no rotation. Solo meant managing both constraints himself.
Taeyang activated [Dungeon Break] and scanned the parameters.
```
[ENVIRONMENTAL PARAMETER: Pressure]
[Current Value: Increases 1 ATM per 10 meters depth]
[Maximum Safe Depth: 50 meters (lethal at 70+)]
[Edit Permission: Available]
[ENVIRONMENTAL PARAMETER: Oxygen Drain]
[Current Value: 1% per 30 seconds]
[Breathing Potion Extension: +200% base]
[Edit Permission: Available]
```
Both parameters were modifiable. He could disable the pressure entirely, or extend his oxygen indefinitely. But each modification would cost SIP, and he didn't know what the boss would require.
Start conservative. Modify only what's necessary.
He reduced the oxygen drain by 50%:
**[System Integrity Cost: 8 points]**
**[Remaining: 92/100]**
Now he had twice as long before running out of air. Enough to clear the dungeon if he moved efficiently.
The first floor was a submerged antechamber filled with Drowned Guardians — corpse-like creatures wearing ancient diving suits, their movements slowed by water resistance. They were durable but predictable, and Taeyang's modifications made them trivial.
**[Drowned_Guardian_03: Speed reduced by 80%]**
**[Cost: 3 SIP]**
**[Remaining: 89/100]**
The guardians became statues. Taeyang swam past them, plucking coins and gems from the treasury floor as he went.
The second floor was deeper — forty meters down, pressure building against his equipment. The [Water Resistance] skill absorbed some of it, but his movements were getting slower. His lungs worked harder to draw oxygen from his breathing potion.
He modified the pressure:
**[Pressure reduced by 30% in current area]**
**[Cost: 10 SIP]**
**[Remaining: 79/100]**
Better. The crushing sensation eased. He could move freely again.
The guardians on this floor were stronger — elite variants with weapons that crackled with electrical energy. Water and electricity was a bad combination. Taeyang modified their weapons first:
**[Elite_Guardian_01: Electrical Damage removed]**
**[Cost: 5 SIP]**
**[Remaining: 74/100]**
One down. Four more on the floor. He repeated the modification:
**[Remaining: 69/100]**
**[Remaining: 64/100]**
**[Remaining: 59/100]**
**[Remaining: 54/100]**
The guardians were harmless now — slow-moving statues with dead weapons. Taeyang cut through them with his enchanted knife, collecting loot as he went.
The third floor was the boss chamber. Fifty meters deep. Maximum safe pressure. Beyond this, the dungeon became lethal.
The Vault Keeper waited in the center of a massive treasury room, surrounded by mountains of gold and artifacts that had been underwater for centuries. It was humanoid, vaguely — a figure wrapped in diving equipment so old it had fused with its body, eyes glowing with pressure-light behind a cracked helmet.
```
[BOSS: The Vault Keeper]
[HP: 100,000]
[Damage: 500-800 (Pressure/Water)]
[Special: Pressure Crush — Creates localized high-pressure zones that deal massive damage]
[Special: Flood — Rapidly increases water level in boss chamber]
```
Pressure control. The boss's main mechanic was manipulating the thing Taeyang had already been fighting against.
He checked his SIP: 54 points. Enough for some modifications, but not unlimited.
First priority: disable Pressure Crush.
**[PARAMETER MODIFICATION DETECTED]**
**[Vault_Keeper: Pressure Crush — Disabled]**
**[System Integrity Cost: 20 SIP]**
**[Remaining: 34/100]**
The Vault Keeper shuddered. Its pressure manipulation flickered, destabilized, collapsed. The localized crushing zones it should have been creating fizzled before forming.
But the boss was adapting.
**[SYSTEM NOTIFICATION]**
**[Anti-Break Response: Flood intensity increased by 200%]**
**[Vault_Keeper: Flood — Now activates every 15 seconds instead of every 60]**
The dungeon had compensated. He'd disabled one special ability, so the other became four times more dangerous.
Water began pouring into the boss chamber from every wall. Not slowly — torrentially. The floor that had been fifty meters deep was suddenly sixty. Then seventy.
Seventy meters was lethal depth. Pressure beyond what his equipment could handle.
Taeyang's chest compressed. His vision narrowed. Every heartbeat was a struggle against the crushing weight of water.
He needed to modify the pressure again — but he only had 34 SIP, and he still had to fight the boss.
**[Pressure reduced by 50% in boss chamber]**
**[Cost: 15 SIP]**
**[Remaining: 19/100]**
The pressure eased enough to breathe. But the water level kept rising. Eighty meters. Ninety.
The Vault Keeper attacked, driving through the water with a spear made of compressed pressure. Taeyang dodged — barely — the weapon's wake alone enough to bruise.
He couldn't win like this. The flood was going to push the depth past survivable limits faster than he could kill the boss.
One option left: stop the flood.
**[PARAMETER MODIFICATION ATTEMPTED]**
**[Vault_Keeper: Flood — Disabled]**
**[Cost: 25 SIP]**
**[Error: Insufficient System Integrity]**
Not enough points. He had 19. He needed 25.
The water level hit one hundred meters. Pressure beyond anything his modifications had prepared him for. His equipment groaned. His joints screamed. Something in his chest cracked — a rib, probably.
The Vault Keeper swam toward him, spear raised, eyes glowing with predatory satisfaction.
Taeyang had two choices. Use his remaining SIP on survival modifications and flee. Or spend everything on damaging the boss and hope he could kill it before the pressure killed him.
Neither was good. Both might kill him.
He chose violence.
**[Vault_Keeper: HP reduced by 50%]**
**[Cost: 18 SIP]**
**[Remaining: 1/100]**
The boss's health dropped from 100,000 to 50,000. It staggered, its body warping as the modification tore through its core parameters.
But it was still alive. And Taeyang had 1 SIP left. No modifications. No safety net.
Just a knife and whatever combat skill he could muster against a boss that wanted to crush him into paste.
The Vault Keeper roared — a sound that carried through the water like an earthquake — and charged.
Taeyang's body moved on instinct. Dodge left. The spear passed where his heart had been. Counter with the knife. The blade bit into the boss's ancient diving suit, drawing something that might have been blood.
50,000 HP was still massive. His knife did maybe 500 damage per hit. He'd need a hundred clean strikes to kill it.
He didn't have a hundred strikes in him.
The pressure was crushing his lungs. His vision was going gray. His modified oxygen extension was running out, and he couldn't afford to modify it again.
Strike. Dodge. Strike. The boss's attacks were slower than before — the HP modification had weakened it somehow — but not slow enough. A glancing blow caught his shoulder and spun him through the water. His arm went numb.
40,000 HP remaining.
His knife arm was the numb one. He switched hands. His off-hand strikes were clumsy, but they landed.
35,000 HP.
The pressure was unbearable. He couldn't feel his legs. His chest was being compressed from all sides. Each breath was a victory against physics.
30,000 HP.
The Vault Keeper's spear caught him in the side. Not a direct hit — a scrape that opened his armor and drew a line of fire across his ribs. Blood clouded the water around him.
25,000 HP.
He couldn't see anymore. The gray had swallowed everything except the boss's glowing eyes. He struck at those eyes. Missed. Struck again. Felt the knife bite something solid.
20,000 HP.
Air. He needed air. His breathing potion was empty. His lungs were collapsing. His heart was—
15,000 HP.
The boss grabbed him. Its hands were ancient and cold and strong enough to crush steel. It pulled him close, pressure-eyes staring into his face.
"You... are... nothing..." The words came through the water like bubbles. "This vault... has waited... centuries..."
Taeyang drove his knife into those glowing eyes.
The Vault Keeper screamed. Its grip loosened. He pulled the knife free and stabbed again. And again. And again. Each strike weaker than the last. Each breath that didn't come.
10,000 HP.
5,000 HP.
The boss's hands fell away. Its body went limp. The glow faded from its eyes.
**[BOSS DEFEATED]**
**[HP: 0]**
**[DUNGEON CLEARED: The Drowned Vault]**
The water level stopped rising. The pressure began to normalize as the dungeon's rules reset.
Taeyang floated in the treasury, surrounded by gold and the corpse of a boss he'd barely killed, and tried to breathe water that wasn't there anymore.
The exit portal opened above him. He swam toward it with arms that didn't work right, through a body that had been broken by pressure and healed by system reset.
When he emerged in the parking garage, he collapsed on the concrete and didn't move for an hour.
He'd won.
But he'd nearly died. One SIP remaining when the fight started. No modifications possible. Just physical combat against a boss he wasn't built to fight.
The lesson was brutal: [Dungeon Break] wasn't everything. When his ability failed, he had nothing.
He needed combat training. Real training. The kind that would let him survive when the System took his exploits away.
But for now, he lay on the cold concrete, breathing the dusty air of an abandoned garage, and counted the beats of a heart that had almost stopped.
Alive.
Barely.
Still alive.
