When it came to the monster requirements it had for this floor, it decided on only one: the monster must be capable of walking on lava.
It wasn't planning on putting any monsters in the water, at least not now. Its mind could change if it decided that the Invaders were too capable. Truly, having the ability to change its dungeon during an invasion was an invaluable power. If it didn't have it, it would have to err on the side of caution, making its dungeon more dangerous, which would provide it safety but would discourage any weak adventurers, and those were precisely what it needed! After all, it didn't want to fear for its life.
But now, thanks to this ability, it can have a less hazardous dungeon that would attract more people while changing the floor plan to a more perilous one if it sees that the current invaders are having a bit too easy of a time. A perfect plan, although to properly execute it, it needs to actually have the more treacherous floor plan, which it currently doesn't, but there will be a time for that later, when it finishes this floor.
Although experimenting with qi would be a great use of its time too, since it already knew willpower was needed for it to function. This meant that it needed to remake the circulatory system of the blueprint humans for them to function as proper monsters, although it still didn't know how that would work or even if it did work, since it had never done it, so its speculation could be wrong. Regardless of that, though, it first needed to finish its 15th floor to do anything else.
With vigor, The Core scrolled through the monster catalogue, trying to find ones that would fit its vision for the floor. It discarded lava golems since it wanted this floor to feel more organic and those definitely weren't that. Anything too big was similarly dismissed; it wouldn't fit on the islands, but it couldn't be too small either, as The Core wanted the monster to take the attention of the Lava Raller in case it emerged from the lava when the floor was breached by interlopers.
Now that it thought about it, there were a lot more requirements than just being able to walk on lava, which narrowed its pool of candidates more, but The Core didn't mind, as long as there were monsters that fit the description.
The monster that The Core deemed the most suitable was the Melted Sword Spirit. Which wasn't organic like the Lava Golem that it dismissed precisely because of that, but it really liked the monster, not to mention it was one it had never used before, seeing as it only unlocked it after killing 10 invaders, so it was curious about its capabilities.
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It created the monster. Its physical form was that of a sword handle; the design of it didn't matter and could be changed from the default of a simple flamewood one without much of an engraving. The blade part of the sword was made of melted steel that could be controlled by the Spirit inhabiting it to change into any shape, provided there was enough material to work with. The Core could easily provide this, seeing as it doubted any invaders could use melted iron and carbon, not to mention find it amidst the lava.
It embedded the handle into the lava, which caused it to move along the flow of it until the Spirit changed direction at the last minute to stop itself from falling off into the water. The blade part that was submerged in the lava didn't dissolve into it; instead, the mana of the Spirit kept it relatively intact, although some melted stone that the spirit must have deemed suitable was absorbed into the blade.
In spite of the Melted Sword Spirit doing almost nothing, The Core was satisfied with its performance and created more of them along the islands. It also added some melted iron and carbon into the lava to help the monsters battle against the interlopers.
That only left the boss monster seat to be filled. Seeing as it already had swords, it thought it would only be fitting to have a bigger sword as the 15th floor boss.
The handles of the Melted Sword Spirits were their only limiters when it came to size, as well as their own aesthetic sense, of course. So if it increased the measurements, the width of the sword could also increase, resulting in a Great Sword!
A greatsword would be especially useful on the floating islands, as the limited footholds would greatly enhance the weapon's battlefield control aspect.
To aid it, The Core increased the amount of melted iron and carbon in the island, as well as adding some tungsten. Not a lot, for if it wanted to create a battlefield floor filled with living weapons and armor, it would need to upgrade the material they were made from, as it would be placed on the lower floor.
With that done, The Core decided to implant some of the swordsmanship techniques it got from the Invaders' memories into the monsters. Some translation was required, for it needed to be from the sword's perspective rather than the swordsman's, but it wasn't a lot, so very quickly all of the Spirits knew all the techniques. The only exception was the soon-to-be Great Sword, which The Core told to focus on pushing the Invaders off rather than on the techniques that it withheld from it.
The last thing it did was build a pedestal that it placed its core on, moving it from the hole and refilling said cavity, making it seem as if it was never there in the first place. With that done, its new and improved dungeon was complete!
