The Core picked one of the farthest points on the floor as the exit and began digging it out.

  While it was at it, it engraved runes on the stone to make sure no water would escape to the next floor and covered them with sand.

  Then the Core began carving the next floor out.

  This one would be a desert to ensure it would keep up with the sand theme it had going on previously.

  Although it did know that having a pattern wasn't good since it would give invaders a chance to guess what the next floor would include, it just couldn't help itself.

  Besides, if it had several sets of similar floors that had different patterns, then the invaders wouldn't know where one floor set ended and another began, so really it should make more of them.

  Although it wouldn't redo the previous floors, as now invaders were actually coming and that would pass as a safety hazard.

  However, that did mean it should put much more thought into future floors.

  Good thing it had a lot of time to make a dungeon plan; although the Core could admit the plan was looking more like multiple individual floor sets rather than a coherent dungeon.

  That was a result of it completely giving up on expanding, but since it had the chance to advance now, it was going to adapt.

  The beach and ocean floors came from the time it was creating its dungeon with a water theme, in which it used the exact same floor plan as it did now.

  Except at that time it didn't use the desert since it didn't contain any water; instead, it made it when it was creating a Fire Dungeon.

  Obviously, this wouldn't fly now; having a dungeon that was defended by only one element was a serious disadvantage.

  If a dungeon wanted to make its halls unique compared to other dungeons, it would place a distinctive mark on each of its floors in the form of a theme, making its halls that much more distinguishable from any other; at least, that's what the manual said.

  The Core wasn't yet misled by the manual, but the fact that certain things had been omitted by it made it trust it a little less.

  Right now it didn't have a theme; when it was preparing its dungeon to face down invaders, it was scrambling too much to remember to include one.

  The Core didn't particularly care to have one either; its floors were good enough as they were, and everyone would know they belonged to it since it didn't think any of its current invaders had entered a dungeon before.

  Although it did think that it was a nice concept, which is why it was going to use it now with sand.

  Later on, it reckoned it could make another set of floors with a theme, although it didn't know what said theme would be.

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  Previously, while it was making themed dungeons, it usually focused on a magical attribute; rarely did it do a Poison Dungeon or a Brute Force Dungeon.

  It already had a Poison floor in the form of the 8th one, and a lot of its monsters utilized physical might in some way, so making an entire floor dedicated to it seemed redundant with the current dungeon plan.

  Maybe an artificial civilization theme?

  While it was thinking these things, the floor was already done; now the only thing left was to decorate it with sand and monsters.

  Covering the ground with several meters of sand took a while, but it was necessary since desert monsters weren't proficient in digging through stone. Although if it made an underground sandstone golem, it could do so.

  Actually having them would be a good idea; maybe it could have this floor populated mainly with inorganic monsters in the form of the golems?

  They never get tired, which would be an even greater boon since the invaders would need to rest to recuperate from the heat, and they wouldn't give them time to do so!

  With excitement the Core handily changed the direction this floor was going in.

  Then it planted some cacti, making sure to space them apart.

  Next, the Core started working on the light mechanism for this floor, which it had to modify compared to the rest.

  Since this was a desert, it couldn't leave the runes imitating the sun as just the light source; it had to make them an artificial scorching sun.

  Thankfully, it had done so before—multiple times, in fact—so while it remembered struggling with modifying the runes, it now couldn't relate to that, completing them in record time.

  Having to repeat the process several times still took time, but it couldn't skip that as that would cause the temperature to be irregular, being hotter in the center and cooler in the corners.

  Granted, the difference wouldn't be that much, but it was better to be overprepared than to give invaders even a little bit of an advantage.

  Although it did make sure to include a few buried treasures on this floor to give them that much more of an incentive.

  Then it quickly went up to the 12th floor to check how much light was sticking out in the dark floor, and the answer was a lot.

  The light emitted by the light runes was different from that coming out of a Luminous Deep-Eel.

  It couldn't see it, but it could feel it, so it was likely the invaders were going to be quick on the uptake too.

  The Core racked its brain for how to fix it but finally decided to make it so a few stalagmites were coming out of the floor to cover the entrance.

  It didn't help much in the Core's opinion, but it spread them over the floor anyway, except for the part housing algae.

  Then it scrolled through its monster catalog to find any bright underwater monsters, but the ones it did find were poisonous, and that wasn't what it was going for on this floor.

  Then the Core glanced back at the exit; it couldn't see the light in a way that something with eyes could, but it still knew the light coming from runes was rather distinctive.

  The only other option to hide it would be to give this floor a light source, which was also not what it wanted for it.

  With dejection, it created some Luminous Maddening Jellyfish in multiple colors just to cover its bases and scattered them around the floor.

  The light coming from them was magical in nature, giving the Core the same feeling as the light runes on the next floor, it assumed that would apply to the Invaders too.

  Then it returned to the 13th floor and summoned desert monsters to populate it.

  The catalog showed multiple new options that would fit, but it quickly picked sandstone golems, as it had decided on them previously.

  It created a large number, both in the sand and above it, making sure to include multiple miner variants among them.

  Only then did it return to looking for suitable options since it still wanted to have some organic monsters, scrolling a bit faster when it saw a jellyfish monster.

  The Core hoped a future upgrade would allow it to sort through the catalog.

  It picked a few satisfactory monsters, such as the Sandstorm Foxes and Scorching Scorpions, and scattered them around the floor.

  It didn't create a lot, already having populated the floor with inorganic monsters.

  The completed floor cheered the Core up from its disappointment about the necessary adjustments to the previous one.