Apparently, a spirit beast manifests at base strength. This meant they initially take in just enough spiritual energy to manifest and sustain their physical form. At first, there is almost no indicator that these beasts were made of spiritual energy until they rose in strength, unless tested with the right equipment. These base level monsters are extremely weak as even non adventurers in this world would train in absorbing the ambient spiritual energy in the environment and reinforce their bodies to surpass their own innate base level strength.

These spirit beasts would manifest in the outer edges of a dungeon as all of the deceased animals' souls that remained on this plane are attracted towards the center. When they manifest, they would hunt for other spirit beasts and fight to the death. When defeated, the spiritual energy in the monster would flow into the victor creating a stronger fighter. They would feel greatly attracted to the core of the dungeon and fight with others along the way resulting in it growing in strength or becoming the means for another to do so.

This process creates stronger and stronger monsters as you move closer to the dungeon's core. At the center is the dungeon's boss monster. All of the spirit beasts are attracted to the dungeon core that he protects and they become food for him to grow stronger. Intelligent beasts would recognise his strength and stall their fight with him. They often settle down in one area and grow as strong as possible before challenging the boss to take his place and power. These were known as sub-bosses and were immensely powerful in their own right. If they manage to rival the boss in power after consuming enough spiritual energy from countless battles, they would attempt to usurp the boss

An adventurer's job usually entails taking down this boss and sub-bosses before they become too powerful to handle. Their places would be taken up by the lower level spirit beast who would, in time, grow stronger repeating the cycle.

A dungeon’s level is determined by what stage of power the current boss is at. The power level for spirit beast ranges from D to A, then beyond. When a boss is defeated, the dungeon drops back down to D level and slowly rises. Dungeons that are often cleared by adventurers, like the Aerlorhn Forest Dungeon, usually stay around level D and C level.

“As me and my party cleared this dungeon just before running into you, as naked as the day you were born... hmm, could you be considered to have been born that day? Anyways, we cleared this dungeon recently so it is at the very bottom of D level now. The boss is currently weak and is constantly being defeated and replaced while there are very few strong monsters. I had the party split up and subdue each sub-boss and have them ready to fight you when you arrive.”

John mulled over all of the information that was just given to him. It was a little overwhelming but Arther did a good enough job explaining it simply.

“Arther, unlike the Children who your family would take into weaker dungeons to practice fighting as a trial, I feel like the case with me is rather unique. Are you planning on treating me like a newly manifested Spirit Beast? Guiding me to slowly defeat and absorb weaker spiritual beasts until I reach the point of becoming a Sub-Boss, or even a Boss at the core of the Dungeon?” John asked while rubbing his chin in thought.

Arther grinned amusedly “Exactly right, my surprisingly clever trainee.” He said slyly. “Right now, you are extremely weak. Like a base level spirit beast, you currently are at the very bottom in terms of strength but have more potential to grow in a dungeon than most prospective adventurers could ever hope for.

People in this world have strength levels that are split up into the initial level, Intermediate level, Advanced level, Profound level, and a few more higher levels above that.all have 3 tiers within them. The gap grows wider from tier to tier as you increase in power. Most commoners who don’t become adventurers remain at the Initial level.”

John nodded, “So how do Spirit Beast levels compare?”

“Spirit Beast can normally defeat those at a similar level of strength so it takes a Middle Tier Initial Level person to defeat a low tier D level beast. The gap between beast levels rise greatly between ranks and a Team of High Tier Initial level Fighters is needed to beat a High D grade spirit beast. When a spirit beast consumes enough of it’s kind to reach even the Low Tier of C grade, there is a qualitative change in strength and it takes a whole team of high tier intermediate Level Adventurers with good team work, or at least a solo Advanced Level Adventurer, to take it down. As of right now, I am at the lower Tier of the Advanced stage and my team is mainly all at the Higher Tier of Intermediate.”

John followed alongside Arther, listening attentively. He started to look at Arther in a new light. While he may always be messing around, and seemingly incapable of being serious, he was a power house in his own right.

“What about B grade spirit Beast” John inquired.

“The Adventurers Guild sees to it that the bosses in dungeons rarely get to that level. Profound Level adventurers would be required, or a huge amount of Advanced Level adventurers. People of the profound level are exceedingly rare and it's even rarer for the guild to be able to order them around. “

As Arther was explaining, he seemed to ignore the fact that John was in the middle of a fight whenever he was attacked by a spirit beast. Currently, John was battling what looked like a red tinged badger with horns. When it swung its claws, John simply sidestepped the attack and countered by stepping down on its back, effectively pinning it in place.

John raised his free foot and brutally brought it down onto the head of the badger, ending its life. The foe quickly turned into a brown colored light that was absorbed into John.

“Well now John, I think this confirms the hypothesis that Vanessa has been studying in the tower. When a spirit beast absorbs a foe, she hypothesized that it takes in more than just spiritual energy. The qualitative change in strength between levels isn’t simply explained by the high levels of spiritual energy monsters because they are able to defeat human foes of similar levels. She believes that the victor takes in some of the defeated spirit beast’s battle instincts and insights during the process of effectively absorbing its opponent’s soul leading to the huge change in battle power.”

John was momentarily taken aback by this. He looked down at himself and realized that made sense considering that so far he had defeated over twenty of these low level D grade monsters and each time it had become easier.

“Let's analyze your strength” Arther said while pulling out the Jeweled Sphere and glasses from thin air that he must have borrowed from Vincent. He put on the glasses and they turned pink. The sphere scanned John with the pink light.

POWER LEVEL OF. processing. JOHN. SLAYDER... COMPLETE.

Arther fiddled with the hot pink glasses and John waited while carefully observing his surroundings. At first it seemed that the monsters were attracted like a starving man who just got a whiff of food to John, but as he took down more and more of them he became more aware of a newfound basal instinct inside himself. Whenever a spirit beast entered into the range of his senses, he couldn't help but lock on to it. The more awareness he developed for these spirit beasts within his range, he became more aware of his growing desire to defeat them. It was as if he NEEDED to challenge them and he found himself searching for them similar to how they previously were searching for him.

“Very good John. Now that we’ve entered a bit deeper into the Dungeon, your spiritual energy is at the Middle Tier of a D level Spirit Beast and is approaching the Upper Tier.”

Arther continued “While it is evident that you have unconsciously increased your own speed, strength, and resilience, as well as your own innate battle prowess... you have yet to unlock a single magic power”

John thought for a moment and analyzed his body. Each time he defeated a beast, he had indeed felt a minor increase in strength along with the healing and he found himself more and more able in a fight.

“Maybe it’s difficult for my unconscious mind to utilize spiritual energy and convert it into magic power because I come from a world that's barren of it.” John rationalized.

Arther got a devilish look on his face. “I was thinking the same thing. One reason my family threw us children into dungeons is because it resulted in extreme levels of stress on our parts. This forced our minds to grasp the lifeline that was magic. I’m thinking that you may need an even bigger shock than these low level Spirit Beasts that are becoming easier to defeat.”

John had an expression that only revealed a fiendish hunger. “I think you may be right. How about you take me to one of these Sub-Bosses”.