The setup here is unusual, but I feel the negative essence pressure in the room trying to draw in all of the free and unclaimed essence in the area. I even feel a gentle tug on my soul vessel trying to, without effect, rob me of my essence. They're too passive to do anything as aggressive as sap active essence. They won't eat a spell, or block a strike, and I could stand here for days without feeling any effects. Instead the goblins are using this to "recycle" themselves to fuel the growth of the den. It's a delicate balance though, too little essence and the core dies. Too much and it can cause a runaway reaction and collapse or detonate it.

  So, simply put.

  If I smash this, there will be less goblins in the world. And with no living goblins in here, doing so will be trivial. I just need to actually disable it, not blow it up. I don't feel like collapsing this tunnel on top of me.

  Den and dungeon cores are, themselves, a very specific type of non-sapient, non-sentient monster. They coalesce under various conditions, but the main mechanism that causes a core to appear isn't understood. Plenty of theories, but nothing concrete.

  What matters, though, is that when one coalesces, it will imprint on monsters in the region, lure them with Monstrum essence — the equivalent essence that forms the basis of a monsters "soul" akin to how Mortalos and Bestia do for the mortal kyn and beasts respectively — and subjugate them. After that, one will sink itself into the earth, find a nearby cave, or, in the case of dungeon cores, warp the world around it to suit its whims and needs. Both will shape the world, but they go about it in stylistically different ways as they increase in power and magical influence from their symbiotic relationship with other monsters.

  Den cores create natural environs with natural monsters. Like this subterranean goblin cave. Simpler creatures with more basic urges and immediately understandable structures.

  Dungeon cores create distinctly unnatural environments with out-of-place monsters. They can be just about anything — tombs, abandoned towns, temples and even spatially impossible places with abnormal traits as a few examples — and contain monsters that would never exist in nature, and as such are massively more dangerous atop just being a more potent example of the core 'species'.

  There's even a few other types of cores — like any monster species there's countless variants. I'm just glad this situation isn't a puzzle core. They're infuriating to deal with in the extreme.

  This one, though, is the weakest form of a core, and only technically a den core because of it. It's a lesser core. Something that was created by the primary one in order to allow it to spread its influence farther.

  I carefully slide down the smooth ramp down to the goblin pile. The den core is about fifteen feet up, and the tug in my chest is stronger here. The walls of this cavern are just as stony and irregular as the rest of the den, but the moss in here is dim or dead, as the essence that it would use to refuel itself is being consumed by the core.

  I consider how to go about this. I have two phials of Fervora in my pack, but I still feel the sting over wasting my healing phials. They would do the job easily and with minimal effort, but I'd rather not waste them. They're one of the few ways I can reliably call on Sanctus.

  As I walk around the pile of bodies, one abruptly reaches out and snags my ankle with a high pitch scream that makes me jump out of my skin. With a more controlled scream of my own I stamp my un-grabbed foot down on the creatures head to silence it.

  Doing so sends a wealth of freed essence from its dying body — the vital remnants of its Monstrum essence. The spreading cloud is quickly "grabbed" by the pull of the core and swiftly drawn up into its center, brightening it a fair bit.

  That gives me an idea, and makes me refocus to re-scan my surroundings. I start to make my way back up the ramp, but not before taking off a gauntlet to start emitting some free essence from my bare palm. I have a fair store of Ignia held to shape, so I just emit a few motes every few steps to see how far the range of influence of the core is.

  All the way out back at the junction, it's still pulling with the same inexorable force, which means it probably effectively covers the entire den except for wherever the main core is. It's quite potent, which means that it's going to eventually undergo a metamorphosis into a full den core before long, at which point it'll probably be absorbed into the main core again to give it a huge burst of power and influence.

  It also means my plan will be that much easier. It's at a tipping point of power, so I'll just push it over the edge and give it a taste of the essence poisoning that mortals have to suffer from.

  I don my gauntlet again and stalk my way down towards the fighting , which hasn't lessened. Much the opposite, it sounds much more aggressive. The scout must have gotten down there and gotten them riled up. The level of noise allows me to move quicker and mean that they're going to be that much more distracted.

  The path is winding, and takes me ever lower. The occasional wider chamber exists where the core likely once rested during a former stage of growth, but they're all, expectedly, empty.

  Eventually, I come upon a drop, similar to the one I had to enter the den through, but much farther, and down at the bottom I see a landing that sounds like it's looking over an open chamber.

  I set to calling Aero essence for about ten seconds, , and shaping it for another twenty. A modified version of what I did to get Garrick, Serafina, and I down the cliff.

  I manifest the simpler spell, [Skystep], and feel the gentle rush of essence pooling around my feet. Once more I step into the open drop, but a series of dull whumps are all that announce my fall. Far quieter than the active fighting below. I land on the final platform silently and dismiss the spell to drop the last couple inches to the ground.

  Before me is the main chamber. I'm standing up on a raised ledge with a curved ramp going down the wall to my right, with the same cliff and ramp setup on the opposite side. The look gives the chamber an unnaturally symmetrical feeling, even if the details stop it actually being so. Cores like symmetry. Den cores less so, but they still shape their closest environments to be roughly symmetrical if possible.

  Before me on the ledge, having not noticed me yet, is a single goblin warrior with a sturdy-looking wooden shield and an axe that is jeering down into a veritable mob of close to one hundred goblins with various equipment. Looking down, they're all congregating around a single much larger goblin that appears to be beating the entire crowd senseless with its bare hands.

  A goblin berserker dressed in even more tattered tatters that show off it's bulbously muscled form towering over the other goblins at a sky-shattering four feet tall. It's an example of a goblin that has taken in enough Ignia essence to evolve. One of the two most common evolutions alongside a fire shaman. Not a threat to me one-on-one, but a good force multiplier, since it drives its simpler kin to feats of greater violence and empowers their abilities through complex passive spells and abilities. Needs to die first. It'll induce an psychic backlash to all of the ones it's directly connected to which could be a good opening move… But then again, maybe Lan's remote bomb technique would be better? Probably the safer option — the path back up is pretty treacherous and I want this as controlled as possible.

  Remote bomb it is.

  In the back of the chamber, between the two ramps, is a tall rainbow ball of essence that goblins are dropping out of at regular intervals with random equipment according to known goblin roles.

  Unlike the lesser core, that one I will have to break if my plan is going to succeed. But first I'll need to cull the herd down there. Moments like this really make me wish I could use projection spells more effectively. One good Ignia burst down there would easily kill a third of them before the fight even begins. But, such is life — the fact I can even manifest magic at all is a blessing since I didn't used to be able to, so I'll take what I have.

  I kneel down here at the exit and place my hand on the ground to impart Ignia to it in a few places. It's a spell that Lan taught me. Their specialty is preparing a battlefield and using both mundane and essence-based traps and I've found great success in mimicking their style at times.

  [Flare Trap]

  [Rune | Ignia]

  The temporary runes glow for a few seconds before dissipating. The only hint of them being there is a slight hazy shimmer if you look at them from the right angle.

  A case of theft: this story is not rightfully on Amazon; if you spot it, report the violation.

  My retreat covered, I turn to the warrior — still blissfully ignorant and cheering on the slaughter with guttural grunting and shouting — and walk to it casually, hidden well under the din. Once there, I take out one dagger, grab it from behind with my gauntlet over its mouth, drag it back away from the ledge, and plunge my dagger into its sternum and throat before dropping it to the ground and stamping on its neck.

  It begins to break down into freed essence immediately due to the extent of the damage, dissipating at the same time that it finishes collapsing to the ground. That burst of essence from a mid-tier goblin immediately streaks to the core which brightens fractionally, and spits out one small baseline goblin immediately.

  They can only process essence so fast, though. A blessing from the gods such that once the kyn of the world are aware of a den core it's probably not going to get much more time to grow, rather than ramping up in line with raids like proper dungeon cores do.

  So I will be overfilling it before breaking it.

  I peer over the ledge to confirm the berserker's location, then back up a few steps. I stride twice, and toss myself off the ledge out into the room proper — directly in line to drop onto the berserker.

  A couple spot me the moment I'm airborne, pointing at me. They fail to react before I've landed on the "leader" that has been butchering them. A terrible crunch rings out as my boots slam into the upper-middle of its spine. It's driven to the ground unceremoniously with the bones snapping loud out over all of the other noises that are starting to peter off as the room reacts to my arrival.

  While the room is still stunned, I slip my knife into the base of the berserker's neck to immobilize it without killing it — I don't want its wealth of essence being released yet. It has a role to play in what's going to happen before the end of this. It spasms under my weight but then immediately goes still from the neck down.

  I use the last moment of peace before these dumb little creatures process what's happening to scan for anything more capable than a martial fighter. One stands out, a fire shaman, beginning to heft a stick with a glass ball on the end aloft to conjure a spell at me. Its slightly faster reaction times only serve to announce it to me, though.

  I wait fractionally until its begun to store essence in its "wand" and then rip a throwing knife from my bandolier and wing it at the orb. It collides and shatters the glass, venting the building raw Ignia into the space around it in a very satisfying ball of flame.

  I got my fireball, and didn't even need to use magic myself for it. Perfect. It's absurd how much they hate fire, yet Ignia is the only essence they know how to use and are almost exclusively comprised of.

  Everything from then on becomes a dance of constant motion. The goblins react at once to the single threat in their midst. They outnumber me, thus they must be able to defeat me. It makes perfect sense to the simple mind of a monster like this.

  I identify a spot on the ground that will be my personal fortress, falling back on my most comfortable style of fighting — something from my homeland. The style was called "The King's Fortress" and revolves around keeping centered on one spot and using every resource and ability you have to control that space in totality. It pairs perfectly with Lan's teachings to allow enemies to overextend before punishing them and Garricks for deliberate action in a fight.

  I keep one hand free, swinging my knife in wide sweeps to ward off the smarter goblins that can recognize a knife. All of the others rush in and are met with the battering, crushing, impacts of my free hand, elbows, knees, or feet.

  I don't plan to kill all of them right away, so I leave the mid and higher-ranked goblins clinging to life with strikes intended to break bones and cripple without actually killing them. I'll need their essence before long.

  Crunch after resounding crunch ring out with each heavily amplified impact, with almost none of them getting back up after receiving one. I even hear a trio of blasts as some goblins find my runes on the second floor. But as I plant myself and knee a jumping goblin in the chest — cratering its torso and sending it away in a shower of essence — I feel a stinging pain in my leg as a goblin gets inside my guard and jams a wretched little knife into my thigh. Little bastard creature managed to find a spot between two plate segments.

  Reacting smoothly and calmly aside from cursing, I grab the goblin by the face, manifesting one of my quick and easy spells with a bit of stored Ignia.

  [Cauterize]

  [Touch | Ignia]

  My gauntlet starts to hiss and crackle instantly as the goblin tries futilely to thrash away from its bane scorching its face. I toss my newly molten companion at a group of coordinated looking goblins that are advancing at me, bowling all of them over. Before the spell fully dissipates, I rip the tiny dagger out of my leg and place my gauntlet on the wound to burn it shut.

  It dreking hurts. Worse than the stab, but I don't know if they had something on the dagger, so I can't risk it.

  Over the next minute I switch to killing blows, taking out my second knife and releasing my held Ignia and forcing it into my knives, which immediately starts to emit licking waves of raw heat, shimmering in a heat fog.

  The remaining goblins — about a quarter of the original total — all freeze on seeing the blades bearing their bane. Momentarily stunned the way most monsters often are on being exposed to their banes. But I give up my personal fortress and start to move through them. When my first blow lands — the dagger scything through the creatures neck like a hot knife through goblin-neck butter — it awakens the room again and the monsters surge forward at me as one mass.

  A mass of borderline insensate, unthinking, monsters who are frothing mad that the concept of fire dares to exist. Again, despite the fact that it's one of their favorite things to use to cause problems when they can. Absurd.

  I take the side of fire, though, and lay into them. Two or three goblins die in each swipe, or are kicked away to buy space for myself. Before long there's a sole goblin remaining. A warrior. Unlike the cowardly slimes, most monsters will never back down. Goblins are no different in that regard.

  The warrior shouts a nonsense sound. Not mad about the slaughter that's happened here. No. It doesn't care in the slightest that it's the last goblin in this entire den. I'm here. I'm alive. And for a monster, that's unacceptable.

  No deeper thoughts, no deeper meaning.

  Simple. Like monsters are supposed to be.

  It throws itself at me wildly. raising its axe to try its very best to kill me. I step to the side of the overhead swing, bringing my knife up in its wrists path and letting it sever its weapon hand through its own efforts. I'm not cruel, though, so not even a quarter second later I separate its head from its shoulders and kick it to the ground as essence bleeds off of it rapidly.

  Looking around, there's probably 20 goblins remaining alive — if disabled. I gather the most advanced examples of their kind, and drag them over to the small, crude, dais beneath the main core into a chattering, biting pile.

  The core is throbbing and releasing pulses of rainbow energy into the room. It's desperately near a total collapse, which I will look forward to. Cores like this emit dozens or hundreds of types of essence depending on the complexity of the things they create, which inevitably means that some amount of the essences will be terribly unpleasant to be exposed to.

  I drag the immobilized berserker along behind me by the leg, and it manages to try to threaten me in the only way it has left — by snapping its jaws. Even now, defeated entirely, unable to move, its only thought is to kill me.

  "Why are you allowed to exist on this otherwise kind world?" I ask it without turning around. It snarls and slavers at me in response, the same as when any of them were alive. "Well, if I have anything to say about it, you won't anymore."

  I pin it to the floor, putting a knee onto the side of its head to prevent it biting me and start to conjure [Flare Runes] onto its chest. They send up the horrid smell of burnt goblin flesh — something in the realm of burnt sugar and old shoes. Each of the five are separate enough from one another such that they won't accidentally set one another off, but close enough that when one goes, all of them will.

  After that, I carry it up the ramp towards my exit, glance around to make sure I haven't missed anything and run my route back through my head. Satisfied, I grab the berserker by an arm and a leg, twist in place to build some speed, and then release it to throw it directly at the main core.

  I don't wait, though. The moment it's out of my hands, I release what little Ignia I have remaining in my stores to bolster myself with [A Fire Inside] and hop over the three small craters left by my earlier runes. I make it to the base of the vertical tunnel before the impact happens and a surge of essence of every kind I can imagine and then some strikes me like a physical wall, concentrated by this little tunnel followed by a small wave of fire washing over me.

  Immediately, this lowermost floor begins to shake and shudder, and I take it as my cue that it's time to leave. I hop up about ten feet vertical and grab the side of the wall. A piece of stonework comes away under my boot, but I adjust, planting myself just long enough to leap for the ledge. A couple pieces of it come away, and I almost fall backwards, but I snag a handful of moss on the wall to stabilize and haul myself up.

  At that moment, the essence freed from the goblins killed by the core collapse surges up through the collapsing tunnel — faster than I was planning on — and past me towards the T-junction. I burst into a run, needing to get past that core before it collapses from the surge of essence.

  I make it to the junction, but don't look. Legs and arms pumping as I scrabble, hop, and sprint my way through the cavern. A sudden wave of essences slams into me from behind as the second core collapses, knocking me staggering and rolling before I recover, accelerating the collapse of the den.

  I'm in the home stretch though, so I right myself, and push on to the exit, arriving just as the mouth is starting to fall apart. Thankfully, my jump is clear, since I shattered the makeshift supports on the way down, so I leap up and hit the grassy ground above. I scoop up my codex and sprint for the edge of the clearing, arriving just in time to watch the den fully collapse.

  It's a terrible cacophony that my armor only partially deafens, but by the end there's a huge cloud of dust and dirt thrown up, and a crater about two hundred yards across and maybe fifty yards at its deepest point remaining in the place of the den. In time, the region will probably repair itself and this spot will become a vibrant life-filled grove of esoteric plants and animals, but it usually takes a year or two for the region to process the essence it just got exposed to. Same as me after all of what I just got hit with.

  The wealth of essence is great for personal development — since it's such a huge variety of types in small concentrations. And there's enough for entire parties of people to benefit. It's one of the main benefits of these things on top of practice and experience. Especially in situations where you've added tons of additional essence to the cores by killing the inhabitants.

  I take a deep breath and lean against the tree to take a breather until I remember that I left Serafina alone.

  I check my codex: It's only been about ten minutes all told, so I'm not too worried, but I start to run in earnest back to the path to find her.