The deepest dungeon on record is the Soutso royal dungeon. The exact depth is not known but adventurers have reached as far as floor 213. This depth is not natural; it is an open secret that the kingdom has made a deal with the dungeon, feeding it criminals, prisoners of war and even citizens from its own slums in exchange for materials. For dungeons that are not deliberately fed, the record is 93 floors. Entry to dungeons of such depth are always heavily regulated by their containing country, preventing them from feeding indefinitely off the young and foolhardy.

- Excerpt from Everything you've never wanted to know about dungeons.

Erryn pondered its next move. The end goal was still to find or create some intelligent life, but there was still no visible route to reach that point from where Erryn was currently positioned. With its core repaired and upgraded, now seemed like a good time to build some new floors. Erryn started to dig out new areas beneath the core in parallel to the surface expansion.

This time Erryn dug out four floors at once, for a total of ten. Not only was it a nice round number, but the rooms needed to get progressively bigger to squeeze in the merged slimes and going any further wasn't going to be feasible. On floor ten the slimes literally filled the entire rooms, forgoing their usual blob forms for sharp edged cubes. This was going to be the furthest Erryn could get without finding a new strategy for dealing with monsters.

Now to get the floors registered and move the core... No need to pretend; building four floors in a row without moving the core was purely to put off this moment. The last attempted core move had undeniably become a trauma for Erryn. Maybe there was a way to get the floors registered with the system before moving the core? "System, how many floors do I have?"

Incongruity detected: Mana density on each floor is not within expected parameters. Working... Ambient mana density outside the dungeon has increased since system initialization. Recalculating... Effective floor increased by 5.
Error: Floors exist that are unregistered. Registering 4 additional floors.
Error: Floors exist below core level. Core must be placed on the lowest floor. Relocating core.
Floors: 10 (effective floor increased by 5 due to excess external ambient mana)

Erryn swirled its mana in amusement. These moments of watching the system acting confused granted it a not insignificant amount of pleasure, and this one had been triggered by a simple question. Not only that but the core had been relocated automatically, with a complete absence of blackouts or hangovers. It was utterly anticlimactic. The plus five effective floor thing seemed about accurate, given the mana densities. Erryn confirmed that the system would now let it summon an emperor slime on the first floor without complaining, but aside from counting towards the systems restrictions there didn't appear to be any effect.

Basking its core in the denser ambient mana, Erryn checked up on its surface expansion. It had taken in a couple more villages, but neither contained anything of significance. There were also more travellers on the road, but again no interesting finds. Erryn could now recognise where roads had lay, where fields had been tended, where forests had grown, but still had seen no sign of any living thing. The sky was still an unchanged roiling mass of smoke, with only the slightest hints of sunlight breaking through during daytime. Nights were utterly dark. It occurred to Erryn that most things required light to see. The dungeon had no light to begin with, so it hadn't really given any consideration to the matter once it had breached the surface. Erryn required no light to perceive after all, and slimes didn't have eyes to begin with.

Erryn decided to work on the monster problem next, turning the increased cognitive capacity granted by the new floors towards manual summoning of a giant leech. It did not go well. Even a leech was vastly more complex than a slime. Erryn did have luck summoning big and even giant slimes, but that didn't really get it any closer to its goal.

Looking at the decayed remains of a forest, Erryn considered that just like light, plant life was another thing it had never considered. How many other things had it missed that would appear obvious with a few more floors? Erryn had pine wood as a material, but that was dead and trying to build a tree from it would just result in a tree shaped wood carving. There were also the red and green berry loot items that it was born with, but had never bothered with since laying out its first floor. Erryn summoned one of each and used analysis, but it showed nothing extra. They must be berries of something surely, Erryn thought. It shifted its surface expansion slightly underground to prevent a complete conversion of dirt to dungeon stone, and planted a few. If Erryn was lucky, they would be capable of growth.

They probably weren't. Regular plants needed light to grow, and there was none. The monsters of the dungeon ate mana instead of food, so maybe plants grown from Erryn's berries would be the same, but the monsters also never grew no matter how much mana was available. Although Erryn did get bigger monsters by forcing extra mana into them while summoning... That would be worth a try. Erryn poured its reserve of 50 mana into a red berry summoning, next to the experimental plot of planted berries.

The mana departed Erryn's core as always but the berry that spawned under the soil looked physically normal, albeit appearing far more mana dense to Erryn's mana perception. That only lasted for a moment however. The ground around the summoning site shook and dozens of vines burst from the ground, reaching a meter into the air before curving back down and snaking along the ground. Smaller vines branched off the main ones, some clawing back underground, others snaking off in new directions. Aside from the initial burst site, nothing grew into the air. Analysis listed the plant simply as 'dungeon vine'.

Just as suddenly as the activity started, everything stopped. Erryn's wondering over whether it had reached a growth limit or if something had gone wrong was answered by another analysis, which clearly stated the vine was dead. Mana perception showed that it had lost the high mana density from before its eruption, and also that the ambient mana was somewhat depleted. Here on the outskirts of Erryn's claimed territory ambient mana was a scarce resource. Erryn guessed that this was the same starvation effect the monsters suffered from, with the whole thing operating on a faster time scale. If a higher mana density was needed, Erryn could oblige.

Erryn began to dig out floor eleven. This time it forwent the usual corridors and rooms layout of sharp edges and corners, instead digging out more natural appearing caves and caverns, connected with winding tunnels. Erryn relocated soil from the surface, placing the experimental plot a safe distance from the upward stairs in a dead end cave that could be easily blocked off, and summoned a new vine. It burst forth as violently as before, and quickly grew beyond the plot of soil. Tiny vines branched off and anchored it shallowly into the stone while longer ones burrowed into soil. It spread up the walls and along the ceiling. Erryn didn't want to let it spread uncontrolled throughout the dungeon, and prepared to collapse the experimental cave. The vines growth slowed as it passed the cave entrance, stopping completely a couple of meters down the connecting tunnel. After a short pause, the thicker trunk vines began to pulse with a dim green glow, while the thinner branch vines began to bud, and burst into fruit. Each vine sprouted one or two clumps of berries of a single colour, but there was much variation between vines. Red and green berries were present, but so were blue, yellow, orange and more.

Absorbing some of the berries to get the unlocks on new colours, Erryn noted that they did not immediately regrow. Ordering its dire wolf down to do some pruning, the vine did immediately begin to grow back, but at a far slower rate. The explosive growth was rather spectacular to Erryn, but it seemed limited to the initial summoning. Further experiments showed that berries of all colours produced the same type of vines, and that vines never spread beyond the room they were summoned in. The second point was strange; there was no difference in stone or in mana that delimited a room, so how did the vines know where to stop? Erryn theorized that they didn't, and that the system was somehow directing the growth. Erryn noted the uniform density of the vines across all surfaces in each room into which it had summoned one, and that the number of clumps of each colour was equal in every room. That wasn't chance; that was definitely the homogeneity that the system seemed to prefer. The vines weren't entering the tunnels even at the slower growth rate, and after cutting away a part of the vine the regrowth was in exactly the same place. It was too soon to tell but Erryn would be prepared to bet on the new clumps of berries being the same colour as the originals that were cut away too. So the system didn't just control the initial growth; it was still controlling it even now.

Erryn pondered how it could replicate that effect manually. By manipulating the ambient mana around the vines, perhaps. Given that they consumed mana, they should probably prefer to grow towards a higher mana density. But there was nothing like that going on that Erryn could see. However the system was controlling their growth was completely invisible, and Erryn couldn't think of a way to influence it. Not that it wanted to; without anything to restrict the vines growth to within a room they would soon overtake the entire dungeon. Although the thought of employing the dire wolf as a full time gardener did provide some amusement.

The ambient mana density on the new floor hadn't dropped as a result of the vines, but neither had it increased. They didn't have the same sort of mana concentrating effect that monsters had, so dungeon vines were not going to be a solution to the monster problem. They did give the floor a nice aesthetic though, so Erryn decided to leave them be. It had been a long time since Erryn had taken the time to, for want of a better description, be a dungeon. It may be lacking in monsters, traps and goodness knows what else that it should have obtained at this point, but it could certainly design an aesthetically pleasing cave. Erryn dug out another couple of floors, which the system refused to recognise due to insufficient mana cycling, before turning attention back to the surface.

Realizing that it hadn't actually absorbed any soil yet, Erryn ate up the first experimental vine plot.

New material unlocked: soil

That would have saved a bunch of relocating soil earlier. In fact, Erryn immediately noticed another effect: Assimilating soil now left it in its original form, instead of converting it to dungeon stone. That would be useful for growing large plots of plants on the surface without cutting off its perception, but for now the only effect was that the edge of Erryn's continued expansion became a little less noticeable, had anyone been around to watch.

Expansion was actually getting harder now. Erryn estimated another week at best before it reached the limits of its mana control. It could see a mountain in the distance stabbing into the murk above, that would be interesting both for direct access to the smoke and to see if plant life survived above it. Also just for a proper view of the sky. But that mountain would be out of reach without another way of increasing the distance it could apply its control over mana. Erryn noted that it had yet to encounter any rivers or witness any rain. For that matter it hadn't really seen weather of any sort. Whether that was due to the blanket of darkness that blocked out the sun or something else entirely Erryn didn't know, but it meant that water was going to be another obstacle to non-dungeon life. Looking for landmarks that were within range, Erryn saw a couple more villages that were unlikely to offer anything new, but some ruined walls visible on the top of a nearby hill hinted at something more interesting.