Without hesitating, the car-sized toad lashes out at my defense force with its sticky tongue. In the blink of an eye it gobbles up a dozen ants and archer beetles. Taking control of the archer pods now lodged inside the beast’s gullet, I command them to pierce the beast with their venomous harpoons.

The amphibian quickly jerks back when a couple of the attacks land. Though it doesn’t seem to suffer too much, its reaction tells me one thing.

It can be killed.

An archer pod’s venom is unbelievably potent, that the toad managed to continue its assault even after being stung in the throat is truly impressive. Perhaps it has a minor immunity to this particular toxin, seeing as it lives in the same environment as the pods.

By the time all my minions had scuttled into the safety of the logistics tunnels, it had already racked up 600+ kills.

Introspectively, I consider; there’s nothings forcing me to fight it.

I mean, I know you (Me, but we’ve been over this.) want me to fight it head-on, because it’d be exciting, but I’m not a fool all the time. What am I, your entertainment?

I have little to gain from throwing my animals at the demon toad, killing it in that manner won’t justify the cost and simply leaving it to wander off on its own would be the best solution. Like I said, I’m in no rush to obtain the cavern.

…

I had decided to relocate my tunnel-sealing crew to the opposite side of the cavern so they could continue to work without the toad noticing, and for a time, everything went alright. After blocking off one more tunnel, it started to patrol the expanse, which brought it into contact with my workers once more. While I was able to recall everyone much faster this time around, now that the toad was patrolling the cavern, my efforts were severely hindered.

The toad can’t climb very well, so I set to work sealing the lava tubes which breach the ceiling. While I can’t pile stones directly on the threshold between the tunnels and cavern due to, well, their orientation and gravity, I have no trouble creating the barricade at the portion of each tunnel that levels off. There is a total of 6 tunnels on the ceiling, so I should be occupied for a while before I have to either wait for the toad to leave, or deal with it on my own.

…

After another two days I finish blocking the ceiling entrances, leaving only 4 tunnels left, all of which are in the toad beast’s territory. Water flows through one of the ceiling tunnels, which opens into a waterfall. All I had to do was ensure my barricade in that tunnel had minute fissures in it for the water to pass through. On the far side, I try to keep it as natural-looking as possible, lest any sapients get curious.

I’ve arrived at a crossroads; I could continue reading about magic whilst I wait for Mr. Toad to leave my future cavern, but with my limited mana manipulation skills (Which I have been practicing, don’t worry.) it will take a long time for me to get to the point where I can use it to protect myself. Alternatively, if can get my hands, or domain, I should say, on the powerful fauna who call the cavern home before finishing the magic books, I will receive an immediate power boost.

In other words, it’s important for me to secure my safety as soon as possible. Learning about magic and capturing the cavern can both accomplish this goal independently of each other, however, capturing the cavern has a sooner return on investment, which is essential when my life is at risk from unknown threats.

Am I being paranoid? Nope, there really are people “out to get me,” I’m being rational. I hope.

The gargantuan amphibian isn’t going anywhere. He looks quite comfortable, terrorizing the denizens of the underground expanse like he owns the place. Unfortunately for him, I’ve just filed a property dispute.

I am unable to directly use telekinesis, cut, or merge on foreign animals, and for larger creatures, I can’t even perform it in their vicinity. But I’m in luck, on average, the roof of the cavern is about 18 m above the floor, plenty high enough for me to drop a boulder on top of the irritating insectivore.

Yeah, yeah, it’s anticlimactic, but it’s smart.

He’s not always on the move, even monstrous beasts need to rest occasionally. At the moment he is standing still near a brook which flows out from the luminous pond of rainbow corals and into a chasm recessed in the cavern’s floor. Even if I miss on my first try, there’s nothing stopping me from trying over and over again. Still, I’m confident that I’ll be able to flatten him on my first try. After all, one of the unique aspects of life as a dungeon core is the ability to effortlessly gauge dimensions, alignment, and the like.

Working around the dangling blue-glowing mucus strands, which I now know to belong to massive carnivorous glow worms who’ve somehow burrowed into the solid stone that forms the ceiling, I carve out a, likely overkill, 3 m wide boulder.

Without hesitating, I free it from the ceiling and let gravity take care of the rest.

The boulder plummets downward and instantly flattens the toad. As it impacts the cavern’s verdant undergrowth, several birds take flight from the nearby fungus trees and I witness 2 dragonflies capitalizing on the pandemonium to score an easy airborne meal.

Mr. Toad is essentially soup. Amused by how easy it was, I begin to laugh maniacally. I am the greatest dungeon core ever!

Free at last to finish fortifying the remaining 4 lava tubes, I set the dungeon helpers to their task.

…

This time it only took a little over a day to finish, in large part because I’d worked ahead and accumulated excess rhyolite. There were 2 noteworthy observations I made. The first observation occurred a few meters down each of the tunnels that lead deeper into the crust; I noticed a layer transition from rhyolite to limestone, which is odd because I can’t fathom how a thick igneous layer of rhyolite could form on top of a sedimentary limestone layer. The geologic history of this world must’ve been chaotic. The second observation was in the same tunnel that serves as the outlet for the pond; lining its walls is a homogeneous mass of spongy living tissue that was laced with branching veins which pulsed in a manner reminiscent of a heartbeat. I definitely need to investigate this after I’m done claiming the cavern, but doing so any sooner could be risky, it’s giving me some creepy vibes.

Because it requires only very minimal focus, I can work on spreading my domain throughout my new territory while I work on other things. Unfortunately, I can’t take control of a creature unless it was born in my domain or has resided there for a long time, so for some of the larger creatures I’ll have to wait a week or two.

The area I’d carved out to supply the substrate for the tunnel sealing project was huge. It really isn’t anything more than a tangle of passages with no clear pattern other than minor features which serve to reduce the likelihood of a collapse. While the tunnels might be narrow, their total volume is nearly equal to that of my ember blossom room. Furthermore, they span an incredibly wide area which runs across the whole territory of my dungeon, such that all of my previous rooms now have multiple entrances.

With the cavern secured, and my domain spreading into it this very moment, it’s time to resume my magical studies. However, there’s something I want to look into first, it won’t take long.

I’ve yet to do anything with the ingots I’d purchased, in part because I haven’t made any metalworking tools yet. Even so, I have no excuses for not testing my cut and merge abilities on them for so long. According to “The Introduction to Arcane Principles” metals are extremely useful in runecrafting, apparently conducting “activated mana” in different manners depending on the type of metal, purity, temperature, relative motion, manufacturing quality, and several other factors. When mana is passing through a rune, it becomes “activated” and can be conducted by certain materials, which is supposedly essential for the rune to function. I don’t know why that is, or what it really even means on an intuitive level, so I’ll need to get my hands on some more advanced books.

Anyway, my point is, you need metal in order to create effective runes.

Wrapping my sense around a half-kilogram copper ingot, I attempt to make a cut.

While I do succeed in chopping it in half, rather than producing one of the clean cuts I’ve gotten so used to by now, I’m left with is a jagged edge. Trying again on a chunk of iron, I’m met with identical results.

This is troublesome, if I can’t cut metal precisely, making runes is going to become substantially more difficult. Well, difficult, but not impossible. Not to brag, but I have more than 85 years of experience as a machinist…

I attempt to merge the two halves of the selected copper ingot together, making sure that it’s the flat surfaces produced by the mold which are being conjoined, not the rough edges my cut yielded.

The outcome closely resembles one of the ugliest butt welds I’ve ever seen in my life. Still, it’s pretty impressive that I can even do this in the first place without melting anything. Again, there’s no difference on the iron either. On a whim, I merge the copper and iron together and am pleased to see that it worked as intended, though it’s still a shoddy weld.

Testing a cut and weld again, I make a new observation. If I use my mana manipulation ability while cutting/merging a material such as stone, the mana being used flows in an orderly fashion. When trying the same on an ingot, I can now see that the mana moves erratically as soon as it comes into contact with the metal. I can only conclude that the reason for my low precision when cutting/merging metals is its ability to conduct “activated mana.” Which I still don’t understand.

I’m a bit dismayed that working with metals and subsequently making runes is going to be more difficult than I’d originally expected, but I’m still determined to make it happen. Also, it’s not like I have much else that’s better to do than learn while I wait for the cavern to become fully claimed and its inhabitants to become controllable.

Before I start reading about the runecrafting discipline, I need to learn about the different kinds of runes, uses of magic, and how to actually perform magic.

The book I’m about to start on, “Theo Kant’s Book for Beginner Mages,” identifies some of the more common applications of magic and explains the basics of using it in its simplest forms. Thankfully Kant assumes the reader has already learned how to move mana at will and is completely new to using runic devices such as wands.

The blockage I built in the tunnel that serves as the brook’s outlet and which is lined with living tissue has minute crevices that allow water to pass unhindered. This also means I am able to maintain a connection to the portion of my domain situated on the other side. Just as I was about to start reading, I detect a presence on the, shall I say, wild side of the fortification. Rapidly shifting my focus in a panic, I do a double take when I notice a posse of 8 familiar human miners carrying ropes and the oil lamps I’d yet to see in use until now standing in the knee-deep flowing water in the lava tube.

Once again, I had neglected my spying on the humans, and this time, there might be repercussions.