Now that the time had come for me to evolve my core, I was a little anxious, to be honest. What if I made the wrong choice and fucked up my build? Cores were an essential skill to any classer, and I had faced the fear of losing it permanently once before. Any choice I made now might be one I could come to regret in the future.

After a moment, I resigned myself to my fate. Hard choices still had to be made.

My first option was [Dark Revolving core]. From its description, I could tell that this core leaned further into the ability to absorb other types of mana. My current absorption could be doubled, though it came at the cost of some mana as well, which might just cancel out the increase if I was unlucky, though I doubted that the system would offer such an option.

Furthermore, the revolving core would allow me to revert converted mana back to its previous element. I couldn’t see the use of such a function right now, but perhaps its future growth would be worth it.

Unfortunately, it only had a small mana capacity, the same capacity as I had now, which would limit my skill usage. Now that I had gained [Sword laser], that weakness felt especially grating.

The next core, or should I say ‘cores’ were the [Twin chaotic cores]. This core somewhat solved an issue that I had been dealing with for some time now. When using [Ghost apparation], I would lose any built-up overloaded mana in the transfer. This gave me a momentary weakness after apparating. Fortunately, [Onyx chain wind] went a long way toward solving this problem, since the skill remained active while apparating.

Beyond the growth potential of this second core, there wasn’t much the core could offer me, apart from the small boost to overloaded skills. Furthermore, it, too, had a small mana capacity, though technically I would have access to twice as much mana thanks to the number of my cores doubling.

All in all, it was the perfect skill if I wanted to specialise in overloaded mana. That was also the thing about the skill that scared me though. If I overinvested into overloaded skills, only to face an enemy that was immune to them, then I would be helpless. Right now, I still had the option of broadening and expanding my future build, and I wasn’t willing to give up that option yet. Choosing [Twin chaotic cores] felt like closing fifteen doors to open one.

All this meant that the final skill was the most appealing one to me. It felt like an all around upgrade that could still switch to a different path if it became necessary in the future.

[Overloaded combustion core] would increase my mana output outright, while also giving me the option to revert the overloaded mana back to normal, giving me some much needed versatility. Perhaps most importantly, the core had a ‘mediocre’ mana capacity, an entire rank above the other options. I wasn’t really sure how large the differences between ranks were, but it felt like a significant upgrade.

All in all, this core had the most versatile growth potential and boasted the largest upgrade when it came to the basics. I felt assured that this was my best option.

I stepped over to the centre of the clearing and called out into the forest.

“Hey guards! I’m going to tier up my core now! Make sure nobody disturbs me while I do that.”

Instead of a verbal reply, one of the cloaked men popped up and nodded slightly, before disappearing again. Huh. My uncle’s guards sure were professional.

I suppose they followed me into the goblin dungeon as I searched for a secluded spot where there was plenty of dark mana. Eventually, I chose the boss room. After decapitating the weak tier 2 hobgoblin and receiving a shitty tier 2 dagger as a reward, I calmed myself in preparation of what was to come.

I sat down in the centre of the cavern and steeled myself as I picked the skill, bracing for the wild rush that came with tiering up core skills.

As I mentally felt the skill appear on my status screen, I felt the mana around me change. [Weak mana sense] picked up on a strange wave of dark mana that was slowly forming around me. Strangely, the mana stayed at arm’s length from me, buzzing like a massive swarm of tiny bees. The hum of the mana slowly intensified, and the mana started to course around me in a stream, almost like they were dancing to their own tune.

Meanwhile, I felt my core shift, unprompted. The tiny black marble undulated like a heart, before stretching until it started to tear. As this happened, intense pain that [Dark form] didn’t seem capable of stopping assaulted my senses. The core felt like it was a part of me. As it tore, it felt like my heart itself was being torn into pieces. After what felt like an eternity, the core had turned into a mat black ball the size of a human eye with several holes in it. The holes themselves were the size of my previous core, the circumference of a small marble. Five of them dotted the core, which looked like a torn piece of clothing, with dredges of black mana barely hanging on like loose thread.

The tearing had stopped, but the pain remained constant. It was only now that the mana gathered around me rushed to save me. From all around me, the humming, flowing mana changed core and headed straight to my torn core, where it sank into the empty holes and tears. The core started to repair itself at§ an unsightly speed, pushing the mana to mend the tears, though the holes remained untouched. Like this, the core recovered.

After a few minutes, it looked fully healed. There was a problem, though. My surroundings were still filled with a veritable lake of mana, the cavern was still flooded with the stuff. Worse, the mana kept flowing into my core’s holes which acted like unfillable chasms, and it wasn’t being used anymore.

Finally, I realised what I was supposed to do. I was supposed to let the core overflow, of course! Overloading was my entire schtick!

Immediately, I sat cross-legged and started to actively absorb even more mana, until my core finally started to overload. The core started to spin upon changing axes as it overloaded, the holes absorbing mana and the round surfaces emitting overloaded mana. All of it flowed around me, quickly replacing the pure mana that was still intent on passing through me. Only now did I understand how long this process would take...

Five hours later, I was finally done. All of the pure dark mana had shifted into overloaded mana, and if I relinquished my control over the stuff, the dungeon might have just collapsed under the pressure. Keeping the stuff under control was taking all of my concentration, which meant that I could hardly leave the dungeon either. In the end, there was nothing for it. I would have to use my skill’s new effect to revert the mana back to normal, no matter how tedious the process would be.

Another five hours later, my surroundings were calm. All of the mana had gone in and out of my core twice, and the dungeon returned to its regular calm. Satisfied with my efforts, a grin appeared on my face. After I had pushed the last bit of mana through, the core’s mat black coloring had returned the deep-black coloration that I was used to, meaning my core had finally finished upgrading. The black orb thrummed with power inside of my chest. Now that it was full, I would only need a single thought to start producing overloaded mana like it was nobody’s business.

Still, the day’s efforts had tired me out, which is why I decided to put off my aura skill’s tier evolution until the next day.

With my mind made up, I left the boss room, only to immediately pause to gawk at the sights outside of the chamber.

Throughout the entire cavern, strange, malformed corpses were strewn. They had some body parts that were similar to a goblin’s, but to compare those creatures to these otherworldly... ‘abominations’ wouldn’t be a fair comparison. The corpses looked like goblin chimeras. As if a few dozen little green goblins had gotten sewn together by magic, but without any thought to the practicality of it. No animalistic shape or anything. In fact, it looked like most of these creatures couldn’t even move, let alone act as combatants. A few smaller corpses were clearer. There was one that had very obviously been a normal goblin in the past. Now, it had eyes in the middle of its fingers, three legs and one foot without any leg that sprouted from its elbows, and a dozen other strange, nonsensical mutations that only served to hinder and weaken the creature. Thankfully, all of these monsters were dead.

As I made my way to the exit, I only found more of the strange corpses. Goblin brutes that had split into two pieces, goblin rogues that lacked a head. Surprisingly, it didn’t look like that was what killed them... Instead, a straight slash across their bodies seemed to have done the trick.

Eventually, I reached the edge of the cave, where I ran into one of the hooded guards. Since I was suspicious and on edge, I kept my hands on the sword hanging from my belt.

“What the hell were those things?” I asked, demanding an answer.

“Mutations, young master.” One of the hooded men replied. As I was about to ask further, an old man dressed like a beggar appeared. The hooded men parted and showed him respect, which meant that this was the returned soldier uncle had sent.

“Don’t throw a hissy fit, kid. We’re the ones that killed the damn things, after all.” The old man said gruffly. He had an unusual beard that parted in the middle. Both ends were tied with a small rope, and the bush of hair atop his head was completely grey.

“How did those ‘mutants’ appear, then?” I asked in a more respectful tone.

“They appeared because of your skill evolution, of course. The mana went wild the moment you began, but those things didn’t start merging and mutating until an hour in. Something about your mana must have merged with the dungeon’s own properties, which led to the dungeon itself changing. As a result, the monsters inside changed as well, since they’re intrinsically connected to their spawning ground. Those creatures rose in level and tier as they mutated, and became stronger as a result. They look strange, no doubt, but their stats started to rise immensely, by the end. Who knows what tier this dungeon had become now? I’ll have to inform your uncle of the developments. Most likely, this place will turn into a regulated royal dungeon, if the mutants reappear.” The old man explained.

The idea that I had inadvertently helped the dungeon grow stronger threw me for a loop, but I supposed it could have a positive effect as well, in the long run.

I headed home with conflicting feelings, and shared what had happened with my parents and Amber, who seemed strangely attentive during my explanation.

The next morning, I headed straight into the forest, to look at the final skill I needed to evolve. [Overload Aura].

[Overload Aura](100%)

Tier 3 skill.

Expelled overloaded mana can be turned tangible at will.

Expelled overloaded mana can be manipulated by the holder and will dissipate into ambient mana more slowly.

Use this skill repeatedly or creatively to increase skill progression.

Tier 4 unique upgrades:

[Method to madness]

Expelled overloaded mana follows patterns attached by the skill holder and can now be used to cast spells.

"Mana must deny itself at your will."

[Crawling road]

Expelled overloaded mana becomes infectious. Any pure mana that comes into contact with it will slowly become unstable itself.

Non-dark-aligned mana's infectiousness is half that of dark-aligned mana.

Unstable mana will slowly become stable after losing contact with your aura.

"Mana must share your pain."

[Part of the great sight]

Give sentience to your mana through sacrifice. Sentient mana can carry out tasks given to it and remains loyal to the skill holder.

"Mana must be elevated above mortality."

My eyes were wide as I stared at the system's notification.

"What. The. Fuck."