The first thing Goblin Cave did was rearrange its floor exits.

Since it had first started digging down, its fifth-floor boss room had led to the rocky stairwell down to its sixth floor, and its sixth-floor boss room had led to the twisting spiral down to its seventh, and so on all the way down. With a push, it thinned the corridors connecting to the bottom of its mana bellows until they crumbled apart, opening up new passages on its fifth floor, and it thickened out the walls on the descending slope until they met, separating the boss into a dead-end room, and the former entrance to its sixth floor into what was now a dead-end fork off of its strangely-branched sixth floor: one secret entrance from the manastone warren around it, entering what was now a forked cave path, before proceeding down to the seventh floor. The resulting restructuring of its mana flow, flow swilling about in a disordered mess before reversing direction through floor six, was disorienting, blotting out clots and blocks of its awareness on its upper five floors for a long moment, before the flow slowly reasserted itself.

It would have to get used to the sensation; it was going to be doing it another forty-three times. Its original sixth floor became a squiggle pit-stop between the two halves of its manastone warren, both entrance and boss room optional branches off the reshaped passage.

It continued thickening the granite wall where the stairs down had been, slowly forming dense spurs of orichalcum and sharp shards of voidglass within the rock, to try to make it as difficult to carve through as possible. All the winding in the world wouldn't help it if the adventuring team could crack straight through the walls.

By the time the adventurers reached what had been the end of floor 5, Goblin Cave was working on floor 8. They stopped, glaring at the wall. Goblin Cave could see their hands move, but it was blind to the meaning behind them. They turned, electing not to carve straight through the wall, and made a line straight for the hidden door that connected to the manastone tunnels. At this floor, it was mostly dark tunnels with sharp vertical segments, which they traversed with no difficulty — short, controlled hops to leap up a 20 foot shaft, casually dropping down with no sign of strain, and always, unerringly, following the shortest path through the maze of corridors to delve deeper.

THEY DO NOT APPEAR TO BE DISORIENTED IN THE MAZE TUNNELS, Goblin Cave wrote up into the sages' chamber, more sluggish than usual with the added delay from reshaping its mana pathways beneath.

"They will likely be directly following the mana gradient," one of the sages said. "I could disguise it, but..."

The question was, what would actually help. So far they had casually and without any issue killed every goblin they had come across, including the bosses. At floor 5, they were only level 4 through 6. Did it have anything it could throw at them that had any chance of killing them?

Its goblin village... if it killed them all now, and the sages managed to disorient the adventurers enough, and they didn't have a mechanism for simply blasting through the stone, then it might be able to construct a soul conduit to get them to spawn again as a force of [Ogre Champions], nearly three score strong. Spending its mana to spawn them at higher levels would genuinely bankrupt it, despite its enormous mana count, and it had no sense of whether or not they would be useful.

The goblins were, ultimately, goblins. Even the mana goblins were pitiable, crude creatures, brutish and squabbling. It had enjoyed seeing them act — the first things of its own it had ever seen genuinely act within it. And now, for what? To provide it a fractional increase in soul growth, so that it could produce a handful more ogres? It felt bitter.

No. If the nature of the system was to flense out all mercy, all curiosity, all waste in favor of a sharp, efficient chart of income and expenses, costs and payments, optimized level-grinding routines, then it would be better to be flensed apart than give in that last spark of something worthwhile outside of the system's quantifying gaze. It would find some other way to fend off the adventurers, or it would die.

SEE IF YOU CAN HIDE MY MANA FLOW FROM THEIR SENSES, it wrote.

The sage cast again: staff thumping on the dirt, and another perfect bubble of non-interacting mana burst out, expanding in all directions with the faintest ripple of pressure. When the wave hit the adventurers, it... bent, wrapping around them and jangling dissonantly, forming a wobbling mass of strangely-interacting mana, constantly seeming to tug and twist in different directions.

"Fuck!" one of them swore, casting... something, some kind of dispelling technique that failed to meaningfully erode the strange mana. When they next made it to a crossing, they looked between the two passages — one ink-black, walls lined with shards of voidglass (that had, so far, shattered under their skin when they reached out to grab it, rather than cutting into them), the other, slowly strobing manastone, casting fierce red-green lights from around the next corner. They chose the dark path.

Goblin Cave spent the time making the final connections between its original cave and the manastone thicket surrounding them as it blocked off its original stairways down. Its mana reversed direction through each level as it did so, billowing out in disorienting waves. There had been an adventuring group on floor 11: low-level, delving deeper for the first time despite the increased risk and worse experience gain. That made sectioning off that floor more difficult, as it had to work around their mana clouds. It also left them no way back up without traversing several floors of its manastone warren. Unfortunate for them.

The core-cracking team kept descending, slower. They had some other kind of directional skill, or at least some other method for finding the right path; when they came to a fork, or a messy set of interlinked chambers with a dozen exits in all different directions, they took the shortest, most direct path deeper nearly half the time.

Goblin Cave opened up a series of mana pipes, flooding an upcoming section with sharp, choppy waves of mana, forming a screeching, dissonant whine all through the mazy switchback section. When the adventurers entered it, they didn't even flinch. No external sign of anything, aside from more hand signals. It was not looking good.

It could make the maze as complex as it wanted. What that was, was an attempt to dissuade with confusion, with wasted time, by slow wearing down of their resources. Their time, it was maybe wasting. Otherwise, it didn't think it was taxing their resources at all.

They descended, as Goblin Cave tried to keep up with rethreading the path through its floors. Its original goblin caves were the only section with spawns set up, and on the increasingly-rare times their route took them through the center of one of its old floors the mobs still had no chance, even as high-tier goblins shaded into low-tier hobgoblins.

Ultimately, it was a low-level goblin dungeon. It had attracted the attention of adventurers of far higher level. This was the consequence of its actions, that it had spent five years contemplating the nature of mana effects, and decades stagnant before that, rather than striving day-in and day-out to kill more, to entrance adventurers into it and ruthlessly cut them down. Who was to judge whether it had made good use of its time, in exploring thought and science, art and interaction? The system was. The cosmos bent under its sway, and all under its dominion had little choice but to hew to its rules or die.

"Oh, fuck this," one of the adventurers snapped, after they hit a dead-end that had opened a hatch over them, drowning the room in regal acid. It steamed over their bodies, boiling up into a caustic fog. The adventurer powered up a spell. They extended their arm out ahead of them, palm facing outward, and a beam of violent energy burst out, vaporizing the rock in a cataclysmic eruption, carving straight through the space between floors and then out into the next... and then past that, and past that again, forming a new tunnel four adventurers astride, walls dripping with molten rock, penetrating directly from floor 12 to floor 15. The one positive point was that the adventurer leaned to the side, hand pressing into the still-molten rock, breathing faster. A sign of exhaustion, however minor.

The massive breach in its mana pathways sent its senses into a churning maelstrom. Its mana currents plumed up the half-molten scar, tangling discordantly with the foreign mana still radiating out of the dripping rock, and in patchy pulses it felt and then lost feeling in its upper floors, before the mana currents reformed and sluggishly started imparting information again. It was quite unpleasant.

The adventurers trudged downwards, absently slaying its floor 14 boss, Gragluk the Gnarled, an empowered [Goblin Warlord] — they had bored into its chamber in a lucky shot — as they went. They at least didn't try the energy pillar spell again immediately.

That energy pillar... slowly, probably uselessly, it further thickened the shell around its core. It had taken visibly longer to melt through manastone compared to raw granite, and there were still rough-edged crags where its spined pins that had bolted the manastone to the granite had withstood the influx of energy much better than plain granite. Surrounding its core, it added hexagonal panels of serpent obsidian, to reflect some measure of the energy, and thicker slabs of orichalcum beneath, to soak up as much mana as possible, threaded through with a dense fractal interface of conductive lines of mithril, to suck up and dissipate incoming mana.

At level 1, a 5-level advantage conveyed an overwhelming advantage. At level 10, something at level 20 was nigh-undefeatable. What hope did its level 66 [Ogre Champion] have against five level 100+ adventurers? What else could it possibly throw at them to stop them? Its enormous mana-resonance chamber, perhaps, but that was if they actually moved through it and didn't simply slice through the ground beneath it.

It had at least reached it in its frantic reconnecting process: floor 26, while the adventurers were still on floor 15. It did have a lead, for all that was helping. It routed the new mana flow from the old cavern in the middle, out into the torus, and then on the far side of the torus, halfway around its circuit from the entrance, it thinned the walls between the floors. And then it dumped more and more mana into further thickening the rock everywhere else, heavily doping it with magical metals, adding complex fractal wires through the rock to catch and dissipate mana. It hadn't experimented much with catching and diverting high-energy mana, but it had experimented some — the immense mana collider was proof of that — and so it had some ideas. Something to force them to follow its path, rather than melting their own, at least. If nothing else it had made could impact them, an enormous wall of high-energy mana might do something.

It would only have one shot. While they descended, it made its final preparations.