Isekai Dungeon Architect

The tunnel leading to the "repository" felt less like a passage and more like an artery. The walls pulsed with a soft, rhythmic light, and the air grew thick with mana so dense it was like breathing syrup.

Thankfully, only Qwy and I were seeing and sensing these changes.

To normal people, this place would seem like any other dungeon corridor... just a little eerie.

Qwy led the way, her flight now a series of graceful, gliding movements, her form seeming to absorb the ambient atmospheric Mana.

Through our bond, I felt a profound sense of rightness, as if she were a key sliding smoothly into a lock the more time passed inside the dungeon.

"Are you sure about this, Miss Aria?" Cass finally whispered, his voice barely disturbing the heavy silence. "This mana... it doesn't feel welcoming. It feels... proprietary."

The worries came from not only his mage's intuition, but also his innate sensitivity to danger.

As someone who knew of his weaknesses, he had developed a powerful danger alarm.

"Exactly," I murmured my answer to him with a reassuring tone, my eyes fixed on the glowing chamber ahead. "We're not breaking any rules here. We're simply accessing what should belong to those who claim it."

Seen from the outside, the chamber itself was a perfect sphere, its walls seamless and polished to a mirror shine.

In the center, hovering a foot above the floor, was the "treasure."

It wasn't quite a chest but instead, a complex, interlocking knot of silver and obsidian filaments, shimmering with contained power— a three-dimensional symbol made to depict a security file or at least something that was 'safe' to access.

The first look at it sent a shiver down my spine, and the second made my heartbeat rise just as quickly.

"This is it," I whispered under my breath, my architect's senses buzzing. I could see the flow of energy around it, a protective shell that would vaporize any brute-force attempt to breach it.

[ "Caution has been advised while interacting with the open public resource." ]

Rose has been silent for a while, but hearing her voice strangely comforted my heart.

Physical interaction with this 'treasure' would result in nothing; even simple magic may not work on something so profound.

But to me, with my guest privileges, it presented a simple interface, one with a code not too difficult to breach.

"Be careful, you two."

I reached out, not to grab, but to interact with the treasure.

-Ooooooooooooong!

I focused my will, channeling my {Material Appraisal} and {Material Collection} skills simultaneously. It was the equivalent of right-clicking and selecting "Extract All."

-Zaaaaaaaaaaaaaa!

A knot of light unraveled, covering the entire chamber in its warmth.

The treasure didn't explode. It dissolved into three distinct streams of energy that flowed towards me.

One, a torrent of pure data, slammed directly into my mind. The second and third coalesced into physical form, dropping with a soft clink into my waiting hands.

[ "New Blueprint Acquired: Material Conduit (Novice)." ]

[ "Creation Units (+50)" ]

[ "New Materials Acquired: Mithril Shard, Arcane-Resonant Alloy." ]

The data was expected, the Essence Points a welcome bonus. But the physical objects were a surprise.

In one hand, I held a dagger. No, a short sword.

It was impossibly light, forged from a metal that seemed to be solid moonlight: the legendary mithril. Its blade was etchedwith fine, spiraling patterns that glowed with a soft, blue-white luminescence.

In my other hand was a ring, crafted from a dark, coppery-bronze metal that seemed to drink the light and Mana around it.

Set in it was a tiny, polished cabochon of a stone that looked like a fragment of a starry night sky.

"By the gods..." Cass breathed, staring at the mithril blade. "That's... that's a king's ransom right there."

The kind of surprise present on him right now was comedic to me; I almost chuckled at that adorable, surprised face.

"Let's see what we're really holding," I suggested, focusing my {Material Appraisal} on each item.

[Ding!]

[Appraisal targets have been identified.]

A translucent blue screen overlaid the mithril sword.

============

[Mithril Shard-Blade]

Classification: Rare Crafted Weapon.

Material: Pure Mithril, Mana-Iron Alloy.

Properties: Extreme Hardness & Lightness, Innate Mana Conduction (High), Self-Sharpening Edge.

Note: Blade responds to the wielder's intent. Capable of channeling spells and cutting through non-physical barriers. A blank slate awaits its owner's signature.

============

"A blank slate..." I muttered with a pleased smile. This wasn't just a weapon; it was a developer's tool, perfectly suited for someone who might need to debug magical barriers.

'OP.'

I then turned my attention to the ring.

============

[Unknown ring]

Classification: Unique Artefact (Incomplete).

Material: Orichalcum, Spark Gem.

Properties: Spatial Anchor, ???, ???.

Note: This ring is one of a pair. Its primary function is dormant. It appears to be a key, but the lock has not yet been found.Proximity to its counterpart may reveal its purpose.

============

A key. Of course. The dungeon wasn't just giving me loot; it was giving me plot coupons.

The sword was for the now, the ring was for later.

"This is more than a signing bonus," I confirmed, my voice low with realization. "This is somewhat of a... provisioning package."

I slipped the ring onto my finger, which felt cool and strangely inert. The mithril blade, when I gripped its hilt, felt like an extension of my own arm, its weight negligible, and its balance perfect.

"Don't you think there's something-...!"

That's when the silence broke.

-Thrrrrrrrrr...!

Cass' voice wasn't the sound that shattered it, but a sensation— a deep, resonant thrum that vibrated up from the floor and into our bones.

"Qwy!!"

The gentle pulse of the chamber walls shifted to a frantic, strobing beat. Red light flooded the spherical room.

[ "ALERT: Unauthorized Core Access has been Detected." ]

[ "The dungeon has initiated the Containment Protocol." ]

The single entrance we had come through sealed shut, not with a slab of stone, but with a solid wall of crystallized mana.

"We're trapped!" Cass cried out, his staff flaring with defensive light.

"...fuck." I cursed, my mind already pulling up my mental map. "The dungeon has quarantined us. It has flagged us as a virus."

-Zaaaaaaaaa...!

My mental HUD flickered frantically as the familiar layout of the sector glitched and re-drew itself.

The safe path to the exit was now highlighted in crimson, marked with new, aggressive icons.

The chokepoints I had noted earlier were now active, swarming with what my architect's vision labeled as [Dungeon Sentinels(Lv.15)]— humanoid figures of solidified dungeon walls, their forms flickering like newborn pixels.

There were tens of these stone figures throughout the new path, but that wasn't even the worst thing about this situation.

My eyes were drawn to a new, massive signal moving to intercept us. It was slow, deliberate, and its designation made my blood run cold.

[Dungeon Warden: (Lv.30) System Defense Golem]

"We can't go back the way we came," I shouted on top of my lungs, my voice tight as Cass' grip on his staff.

"The exit has been moved. We have to push through them somehow!" I hefted the mithril blade, my mind mapping the safest exit available to us right now. "And we have to get through them!"

"Grrrrrr!"

-Swish!

The first of the Sentinels phased through the far wall, its arm extending into a blade of sharpened light.

Cass didn't hesitate this time, his survival instincts kicking in.

-Ooooooooooooong!

A bolt of fire was shot from his staff, striking the creature square in the chest and making it flicker violently.

I moved on instinct as well, the mithril blade humming in my hand.

As the Sentinel lunged, I didn't parry; I simply let the blade pass through the creature's form.

-Krrrrrrr-Tak!

Where the mithril touched, the mana construct unraveled, dissolving into harmless sparks with a sound like shattering glass.

"It disrupts their cohesion!" I shouted to Cass. "Aim for destabilization!"

He nodded with tears visible at the end of his eyes, his fear now channeled into a mage's focus, altering his spells from blunt force to precise, disruptive frequencies.

-Oooooooooooooooong!

-Boooooooooom!

We fought our way out of the spherical chamber into the corridor, which was now a chaotic mess of flickering lights and grinding stone.

Had it not been for my Spike-traps and the ample CU I had thanks to the previous quests, we would have, most certainly, been dead by now.

"Qwy!!!"

-Ooooooooong!

Qwy was a blur above us, her {Glimmer-Pew} shooting out, not to damage, but to highlight weak points in the forming Sentinels and dazzle them, giving us crucial openings.

"Haaa! Haaaaa!"

It was a running battle. We were no longer adventurers looting a dungeon; we were a system process desperately trying to avoid being terminated.

"Damn it...!"

We rounded a corner, and there it was.

The path to the new exit was just fifty yards away, a shimmering portal of calm, white light. And standing between us and it, filling the entire corridor, was the Warden.

'How the hell...?!'

It was a juggernaut of stone and crystal, ten feet tall, with a single, blazing red orb for an eye. Its fists were massive blocks of granite, and the ground cracked with every step it took towards us.

"We are sooooo dead!!"

Cass skidded to a halt, his face ashen. "We can't possibly fight that!"

The Warden raised its fist, mana gathering around it like a swirling storm of lethal code.

I looked at the mithril blade in my hand, then at the ring on my finger. We had the new tools, but we were hopelessly outmatched. The dungeon had accepted my access, but it was now testing if I was truly worthy of the privileges and the loot it had granted.

"Qwy...!"

"Miss Aria!!"

The gargantuan fist had already begun its descent.