The town of Berju and its surroundings are utterly unremarkable. The area offers no unique products, is of no strategic importance and produces sufficient food to support itself without relying on import while not having a sufficient excess to export. However, recently this lack of note has become the area's greatest strength, for it has been spared much of the horrors of the war. None of the hex bombs that plague the capital or fortress cities land here, nor do lesser attacks by magics or men afflict us. The largest effect of the war has been from the conscription of much of the adult male working population into the army and the arrival of refugees seeking safety. It is saddening to see children displaced by war forced to work our fields that have been abandoned by those who have left for the front line, but given the alternatives I feel that complaining about our situation would be so ungrateful as to induce the wrath of the gods.

- A letter from Baron Blon, the steward of Berju and attached lands

The town Erryn had discovered was surrounded by tall walls of stone, the outside so smooth that it was difficult to see the joins between the blocks it was built from. There were overhangs, buttresses and towers. It was thick enough for one of Erryn's largest slimes to sit comfortably on top. The gate was equally impressive, made from thick iron bars and heavy woods that had not yet rotted away. It would be an impressive defence for most things trying to invade the town. Erryn was not most things, however, and with a push of mana the walls... did not became a part of the dungeon. That hadn't happened before; the walls rejected the incursion of Erryn's mana.

So these walls also protected the town against invasion by a dungeon? Was that a common thing that happened? More likely they were just protected from mana in general; if dungeons could utilise mana then surely other things could too and there wouldn't be much point building up thick walls without protecting them from mana based attacks. Probing its innate knowledge, Erryn recalled the existence of mages; humans capable of wielding the power of mana. Exploration revealed that the warding extended below the walls too. Pushing up a rampart showed that it also went above. Impressive, but Erryn wasn't going to give up on a source of information so easily.

Erryn expanded around the walls, as well as below ground, butting up against the barrier. With it surrounded, Erryn pulled at the mana from all sides. There was actually less resistance than Erryn expected; the machinery that produced the barrier had gone without maintenance for decades after all and neither would any wall block a foe forever while undefended. Before long the barrier shattered and the town walls fell to the dungeon swiftly after.

The first thing Erryn noticed was that the walls looked a lot newer than the buildings that lay beyond them. The walls were definitely a recent addition to the town. The buildings near to the walls were mostly small and in very poor condition. They were likely to be residential dwellings. On the western side there was only rotting wood littering the floor to mark where buildings may once have been. That must have been an area of slums. Around the gates were larger structures, still standing due to their stone construction. Inns, eateries and shops, perhaps. Erryn found nothing of interest in any of them.

The first useful find was what appeared to be a street of workshops and craftsmen. A smithy contained enough steel to unlock the material, but little in the way of finished goods. An alchemist held containers of reagents still in good condition. There was a weave of mana around the containers, so perhaps the good condition was due to some sort of preservation magic. Absorbing a container simply destroyed it without unlocking anything, so not wanting to waste potential resources Erryn left the rest untouched. The preserved resources from an enchanter next door were left untouched for the same reason; there were materials there that had obviously come from monsters and Erryn wished to find some way to use them to reproduce the full creatures.

Nearer the centre of town were larger shops with wares still intact. Jewellery, weapons, armour and tools, as well as a platinum coin supply. An apothecary had shelves filled with bottles of suspiciously coloured viscous liquids which unlocked nothing, but also preserving containers in its stores filled with bottles of far brighter colours which unlocked a variety of types of potion. The potions out front must have decayed. Erryn pondered the effects of absorbing ancient expired potions, before remembering the quantity of rotten wood it had digested and feeling quite glad it didn't have a stomach.

More than 20 loot items unlocked. Unlocking loot categories.

Available loot:

Clothing? Apparently that was the jewellery. Anything wearable that didn't provide protection got lumped in as clothing. The categories seemed to grant greater freedom in summoning; Erryn had only absorbed steel swords but now found it could summon swords of any available material, as well as vary the design. As loath as it was to rely on the system, it did have to admit this was a useful upgrade.

Closer to the centre of the town were large buildings. Mansions of the rich, guild halls, and other structures Erryn did not know the purpose of. One of the mansions contained a room of books, in which every bookcase was imbued with preservation magic. Erryn didn't know why this one particular owner had done such a thing; there were many bookshelves filled with decayed books it had already come across that no-one had felt the need to preserve. But despite being literate, Erryn was foiled by a simple inability to turn pages... This room was perhaps the most valuable resource uncovered in the town so far, so some way to extract the information from the books here was given a high spot on Erryn's agenda.

That only left the manor at the centre of town. There was surprisingly little of note in there, but a room in the basement unexpectedly proved inaccessible, with the same feeling as the barrier that protected the walls. A pair of armoured skeletons in front of the door reinforced the picture that this room was important, and well protected. This new barrier took longer to tear apart; it did not have the strength of the wall barrier, but the strength it did have was concentrated on a far smaller area. Accessing the room, Erryn found the floor engraved with glowing runes, organised in circles around a central pedestal, on top of which sat an orb the size of one of Erryn's basic slimes. The walls were studded with rectangular crystals which emitted a pale red light. This must be the equipment which projected the barrier around the town. But more important than that was that Erryn immediately recognised the orb for what it was; a dungeon core!

This new core was considerably larger than Erryn's. It was pulling in ambient mana and presumably was the power source for the whole barrier setup, but none of this room was dungeon stone. Was this core dead, or did the runes restrict it somehow? Would assimilating this room be safe? Perhaps, but the chances would be better if the apparatus in this room was powered down first. Erryn tried to pull mana away from the room to stop the absorption, but the other core was stronger. Attempting to claim parts of the wall failed in a new way; as soon as dungeon stone was produced, the core ripped the mana straight out of it converting it back to regular stone. If Erryn was going to lose a tug of war, then it would just have to remove the rope. Erryn built up a bubble of gold around the room, and sure enough the core was unable to pull any mana from it. The ambient mana in the room swiftly decayed to almost nothing, but that also precluded Erryn from moving in. Fortunately Erryn needed to take no further action; as the mana dropped the runes fizzled and the lights went out. Removing the gold shell restored the ambient mana but the core no longer drew on it, and the runes remained inactive. Erryn swiftly claimed the room before anything managed to boot back up.

Unnamed undead dungeon [Withered] defeated. 0 floors captured. Foreign core captured intact. Utilizing to reinforce local core.

Error: Local core unstable, unable to reinforce. Utilizing foreign core to repair local core.

The dull itch in Erryn's core suddenly blossomed into an unbearable tickle torture, making concentration all but impossible. In brief bouts of coherency Erryn saw the crystalline growths on its core contract back into it and the surface smooth over, while the foreign core shrunk. Thankfully the process was over in a few short minutes.

Foreign core retains sufficient material. Utilising to reinforce local core.

Dungeon core upgraded. Maximum mana capacity increases to 50. Mana regeneration increases to 0.0015/second.

That part of the process was far less unpleasant, even if it took longer, and Erryn was able to watch the foreign core shrink away to nothing while its own grew. So dungeon to dungeon combat was a thing the system catered for. It didn't seem that Erryn had killed the new core; there was no resistance at all and the core had a 'withered' tag rather than the 'withering' that Erryn had at the point it accidentally lost its core. But in that case the system didn't really bother differentiating between living or dead cores, which was strange. It was a pity that the system had destroyed the new core without any prompting from Erryn; it may have been a good research material. Perhaps it was another way of the system preventing Erryn from learning something it shouldn't, but since it had resulted in the damage to Erryn's core getting repaired it didn't feel justified to complain too strongly.

With the assimilation of the barrier room, Erryn had now taken over the whole town. It turned its attention back to the alchemist. Until now, Erryn had assimilated whatever it could and absorbed what it could not. Things it had absorbed were either used for unlocks, allowing Erryn to produce replicas at will, or useless things that Erryn did not need like rotten or rusted items or the skeletons that littered the landscape. In that case absorbing them was simply cleaning up. Dungeon instincts insisted that all foreign objects abandoned in the dungeon should be disposed of in a timely manner, lest the dungeon fill up with spent arrows and similar debris, and that had translated somewhat to the surface. The dungeon instincts insisted the same of these boxes of reagents, but this time Erryn could see a future use for them. But what to do with them instead?

What was the difference between dungeon stone and regular stone? By imbuing its mana into stone or soil, Erryn produced dungeon stone and made it a part of itself. But what made it a part of 'Erryn' rather than just a lump of rock with a bunch of mana in it? The core ejection incident had shown that dungeon stone could become 'not Erryn' while retaining its mana and form for a time. Linking back up to the previous floors had not immediately restored the whole thing, nor stopped the egress of mana; Erryn had needed to re-assimilate it piece by piece. That implied some connection between the stone and dungeon core, that once broken could not be restored. Shifting its perception to where the dungeon core met the pedestal Erryn could see a flow of mana, but no structure to explain such a persistent connection. The structure of the link was either too fine to be seen or else was composed of something other than mana.

At a roadblock on the stone, the next question was what separated a copper coin produced by Erryn from one produced elsewhere. Erryn had yet to absorb the junk of the town, and quickly located a few coins. Erryn's own coins were 'reclaimed' rather than the others which were 'absorbed', so there must be something that separated the two. Or was there? It occurred to Erryn that it had never tried absorbing its own features, or reclaiming something from outside. A quick experiment showed that despite assumptions, either skill could be used on either type of coin. Either one broke down the object into mana, and absorption pulled it into the core while reclamation dispersed it into the ambient mana. Apparently there was no difference whatsoever between a coin produced by Erryn and one that was not. Logically that did make some sense; Erryn could not perceive things through a coin in the way it could through dungeon stone. Further experimentation showed that the same applied to other items too. Loot items simply were not a part of Erryn in the same way that the stone was. In that case, the reagents Erryn wanted could be stored easily. Erryn dug out a large room back in the labyrinth and used relocate to neatly store everything it wanted to keep.

More questions remained about how monsters and traps fit in to this. Monsters must have some connection to the core or something to mark them as belonging to Erryn or else Erryn would be able to order around any monster that set foot into its territory, and previous experience had shown that was not the case. That called for more experimentation, but first it was time to do something about the collection of books.