Goblin Cave was as prepared as it would ever be. The rock was as doped with mithril manasinks as it could get, and it had started up the mana resonator. Pressure waves were forming, thrumming through its massive halls, building up more and more resonance as its ring-panels engaged in sequence. Each engagement was a blast of sound, a loud thunk as its coils and plates jerked forward, squeezing the building mana wavefront just a bit tighter as it circled faster and faster, hotter and hotter.

By the time the adventurers reached floor 26, it was a cataclysmic wavefront, shaking stalactites loose from the ceiling of its old cavern floor with each pass. There was just the one corridor out, with most of the rest of the old cavern sealed within a sphere of the densest material it could produce on short notice, half insulation from the resonator and half to prevent the adventurers from cutting straight through.

The hallway from the cavern let out at one of the two thousand four hundred and one junction relays ringing the torus chamber, with a narrow access available between two immense mana regulators. They weren't fools; they didn't blithely step directly into the wavefront. Rather, they waited a moment as one wavefront passed and then they cut to the side, trying to move around the inner curve of the torus without ever setting foot within the massive chamber itself.

Goblin Cave cut the servos to the inner half of the coils, letting the wavefront curve in and crash through the wall, slamming directly into them.

The impact was the highest-energy mana exchange it'd ever felt. It was far too high-energy for [Flame Wisps] to stabilize: the impact burst out as sound and light, bursting arcs of lightning all across its coils, uncontrolled eruptions of heat as the air itself caught fire. The mana shield wrapped around the adventurers, for the first time in their descent, wobbled.

One of the adventurers let out a scream of exhilaration, whooping loudly. "That's almost ley-line level power!" was what they yelled, before the next wave hit them, sending out another cataclysmic release of energy. And again, and again, as each wavefront slammed into the broken wreck of the torus. The adventurers staggered, one manifesting an enormous sword just to slam it through the ground to use as an anchor. They sluggishly pushed forward, even as Goblin Cave dumped wave after wave of mana over them.

But the torus was being shredded apart as they advanced, and each wavefront was weaker than the last as the machine fell into disarray. The adventurers' mana shield wobbled, pluming out a thick haze of spent mana, but as the waves weakened it stopped, until it was the same implacable rock it had been before, with the mana waves breaking uselessly across it.

This was the power of level 100. A power utterly beyond its capacity to damage, or even stop in any way that was meaningful.

This is what it meant that it had not immediately cut down its goblins and reinvested them in the highest-tier mobs it could. It had spent its time unlocking a scattering of profoundly low-tier mobs, useless for practical combat. Regardless of its own feelings, in the eyes of the system, this was all a waste. What would have been better, by the objective measure of the universe, would have been to optimize. To grind for levels. To be both more appealing and more deadly to adventurers within it. To cut away all thoughts and reflections in favor of caring solely about what the system interface told it: experience, levels. Power.

The system being a transcendental experience, a continual unfolding of potential — Goblin Cave could not understand it. Not unless one was hypnotized by the sight of numbers going up.

And now it would die, in favor to give birth to a new dungeon without its quirks and foibles. Something that would, ideally, be more effective at its duties, at endlessly providing experience fodder.

To hell with the system, Goblin Cave thought, and brought the mountain down.

Tons of rock caved in, absolutely obliterating its mana resonator and cutting off all sensation in its upper floors. Its mana currents jolted, shock propagating all they way back to its core in a painful frisson of impact, and by the time it had woven new threads through the collapsed rock one of the adventurers was letting out a bellow from inside. They were pinned: bodies fully intact, still mana-warded, but they didn't have the leverage to move with the geological weight of rock on top of them. The bellow turned into a flash of mana, erupting outward in a sphere, and where it hit rock the rock vaporized, creating a dense orb of burning heat that sluggishly sunk deeper through the rock before slowly fading out. The bottom third of the sphere was full of lava; the upper two thirds mostly volatiles, slowly cooling down to condense as dewdrops of molten rock across the smooth upper slope of the sphere. No air, but creatures such as them were beyond breathing. The five adventurers hauled themselves upright to stand on the cooling rock floor, molten rock sliding off them like so much dew.

Goblin Cave squirmed its mana through the wreckage, boring out tiny pinhole wires to try to link up anything to its upper floors. By the time it had managed to reconnect — the sensation returning to it just as painful and disorienting as the disconnection had been — most of its upper-floor mobs had burst apart from mana failure. So much for its giant earthworm.

The adventurers, however, were... not trapped, certainly. One of them glared through the rock, slowly casting something that shot out flecks of mana, probing through the dense rubble. But they were, for the first time, not moving. The area around their bubble was painful to sense: a blot of foreign mana sluggishly dissipating through the rock, but slowly Goblin Cave was able to seep through the mess.

WE SHOULD TALK, it wrote on the wall of their sphere, ABOUT WHAT YOU SEEK TO ACHIEVE HERE.

"Oh, this," one of the adventurers said.

"They did say—" another one said.

A third adventurer sighed. "At least try to stick to opsec, please."

I FIND IT VERY LIKELY THAT WHATEVER YOU ARE BEING PAID TO DO THIS, I CAN MATCH.

"Oh yeah? What makes you think we're getting paid?" Another let out a bark of laughter at that.

"It's more of a favor, really," one of them said.

The one that had objected about opsec let out a groan. "You're worse than kids, c'mon."

"Gotta say, I am pretty impressed at that trick you pulled," one of them said. The one with the giant sword. "We're about a hundred-fifty floors too high to actually tap into a ley-line, but you did a damn good impression of one."

These people, Goblin Cave realized abruptly, were idiots. It was struggling for its life, and to them this was... a fun afternoon jaunt, with all the levity that implied. THANK YOU, Goblin Cave said, fuming. ABOUT PAYMENT, THOUGH.

"You're, what, a sixty-floor dungeon? Maybe more, if this is what you got for the 20s, but—"

"Stop talking to the target!" the one snapped.

"—What I'm saying is, there's not anything you can pay us with. Sorry, but we'll be taking your core. We get a bonus if it's intact, so try not to struggle too hard, okay?"

The one who had been flicking mana through the rubble spoke for the first time. "It's adamantine," they said. "Two shards. Three if you're intact."

That was... unfortunate. It had heard the term adamantine once before, but... whatever it was, it couldn't synthesize it.

GIVE ME A MOMENT, it wrote, mostly to try to keep them talking for any amount of time further.

Its upper floors still felt foggy. Snaking its attention up through the thin passages it'd dug through the ruins of floor 26 gave it acute vertigo.

WHAT IS ADAMANTINE?, it wrote on the wall of the sages' chamber, and then had to strain to pick up any response through the painfully diffuse mana.

"Ah," one of the sages said. "A perfected metal, produced rarely by only the eldest dungeons. Incredibly rare, even among the most powerful adventurers of this era." They reached into their pack and pulled something out, and Goblin Cave abruptly lost its senses in that room for a moment, its hazy mana twisted away by the abrupt lensing around the... tiny sliver of what must have been adamantine the sage was holding. Red-black and gleaming, with a strange pitted surface. The sliver was thin as a needle and only as long as one of the sage's fingernails, but it alone had more mana density than anything it had ever felt before.

"I came with a shard, to see if you could replicate the material," the sage said, and Goblin Cave wanted to scratch out in enormous letters WHY HADN'T YOU MENTIONED THIS EARLIER?!

It hazily felt out the shape of the adamantine, mana shredding itself apart as it tried to probe into it.

Most materials felt somewhat airy. Mana, like water, soaked through solid stone, if given enough time. There was, in some sense, space within them for mana. That was the primary distinction between plain rock and manastone: the manastone had had some of its empty space filled with semistable mana flows. Manacrystal, a hundred times denser, had mana packed into dense crystalline loops, forming a sharp lattice that needed to be earthed in exotic matter in order to be stable. Adamantine was utterly beyond that. Even the tiny sliver the sage held in their hand represented a significant fraction of its total mana supply.

...but a significant fraction meant that it was less than all of its mana.

Slowly, painstakingly, Goblin Cave mimicked the bizarre convolutions of the adamantine shard's structure. Deep within its lower floors, it poured more and more mana into the inexhaustible well that was the adamantine's structure, feeling the pangs of mana depletion for the first time in ages as its mana dropped rapidly.

It had, by system count, roughly two and a half million mana. A cubic meter of manastone: a hundred mana. A cubic meter of manacrystal: roughly ten thousand mana. A cubic meter of adamantine... the amount of mana was beyond belief. A cubic centimeter of adamantine was beyond it. A burning mote burst into existence on floor 27 as Goblin Cave coiled more and more of its mana together, until slowly a pattern started to emerge.

New material unlocked: [Adamantine]! Adamantine A high-tier mana-storage material, only naturally found within the hearts of planets. Veins extend out from the heart as spires into the lightless abysses of the underworld. Famed as a material for weapons for its ability to hold an edge, as well as its malleability to accept enchantments, it is known all the world over as the king of the perfected metals.

The system pane unfurling nearly broke its concentration. Yet another affront to blame on the system. But...

A tiny cube of adamantine burst into existence and fell to the ground, landing with a solid thunk. It represented more than half of its entire mana supply, roughly a million and a third mana in a half-centimeter cube.

HOW MUCH, it wrote, back down in the adventurer's rock bubble, DOES A SHARD OF ADAMANTINE WEIGH.

The adventurers shared a look. "There's no way—" one of them started.

"Around 25 grams," said their mage.

Its cube weighed 28 grams.

I WILL GIVE YOU TWO SHARDS TO LEAVE IMMEDIATELY, Goblin Cave wrote. AND A THIRD IN TWO MONTHS TIME.

"You can't be serious—", "No way!", "Yeah, right." The adventurers made a cacophony of noise. Goblin Cave spawned the second cube of adamantine just outside of the sphere — they sure as hell noticed it in the process of spawning, weapons coming out and spells pointed in its direction — and then with the final dregs of its mana it dissolved the rock at the edge and let it fall into the bubble with a clang.

"That's— actually adamantine," their mage said, after a long diagnostic spell. "Huh."

"If we kill it now, we'd still get three shards, y'know," one of them said. The one that complained about opsec slapped them in the back of the head. Goblin Cave assumed for being obvious, rather than any moral objection.

Its mana sunk down to the low hundreds and began the process of slowly ticking back up again. It was well and truly spent. Even writing — the act of materializing a thin patina of lumenrock — scraped at the limits of its emptied mana pool.

I HAVE TASKS THAT WOULD REQUIRE THE AID OF HIGH-LEVEL ADVENTURERS, it wrote, hopefully not visibly slower than usual. I COULD HIRE YOU TO ACCOMPLISH THEM, FOR FURTHER SHARDS IN THE FUTURE.

Bribery. It all came down to power and bribery. The thought was disgusting...

"Yeah, that works. Not like we really cared that much about collecting cores anyway."

...but Goblin Cave would take the victory, assuming the adventurers got out.