On the way back to the academy, Nidhogg maintained his walking routine to train, but his pace was much quicker due to his strong sense of purpose. Wearing a pale mask, Nidhogg moved swiftly, carrying not only a knight's greatsword but also a bag containing the heads of three "black wizards." He wondered what kind of reward Mentor Pearl Arnose would give him for this achievement upon his return to the academy.

Striding forward with anticipation and a wry smile, Nidhogg decided to let Mentor Arnose worry about the rewards; the real prize was the knowledge gained from the mission and the practical training it provided.

Twenty days later, in the Forest of Thornspines, Nidhogg sat at the peak of a massive tree. Cloud cover shrouded the moon and stars, with the eternal flame providing the only light as Nidhogg examined the "demonic contract," using his soul to interpret its text.

"What wondrous writing! To comprehend its meaning through one's soul—that seems to be a natural imprint aligned with certain soul waves. It's incredibly fascinating. Besides the 'catalyst,' the text itself might be invaluable for future studies on soul applications," he mused, his eyes burning with interest as they trailed over the contract and its small, dark flame that bore no heat or light.

Touching the black flame gently, Nidhogg noted a sensation akin to "burning liquid."

"This catalyst... it's just... remarkable. Even at first sight, my soul quivered with excitement! It possesses perfect compatibility and great potential. I am eager to see what kind of animated fire elemental magic life I can create using it," Nidhogg thought with anticipation.

After finishing his study of the "demonic contract," Nidhogg took out the final piece of shattered mirror he had collected. He had examined it countless times on his journey, but the fragment remained nothing more than a piece of metallic-tinted glass, showing no anomalies. Nidhogg sighed, uncertain whether his knowledge level was insufficient or if the glass truly was a mundane fragment.

Having reached no conclusions, Nidhogg put away the glass shard and took out his crystal ball.

Mental Power: 30

Magic: 285~310 (maximum increased by one)

Constitution: 36

Stamina: 189~190

Strength: 91~294

Vitality: 162~296

Gazing at his training results, Nidhogg was lost in thought. Although the months of rigorous training had significantly enhanced his body's base attributes and unlocked some of the potential of his 36 Constitution, it was far from fully realized.

High stamina offered many benefits, as Nidhogg had experienced: boundless energy, endurance, a good appetite, and heightened senses, all seemingly linked to stamina. While not directly enhancing combat power, it served as an "accelerator" during regular training, allowing Nidhogg to devote more energy to practice and focus more intensely on his studies, boosting efficiency.

As for strength, Nidhogg's range of 91294 marked a qualitative leap from his previous 35120, though calculating attack potency in terms of elemental wizardry power was different. For Nidhogg, his pure strength translated to a power level between 9 to 30 degrees.

Strength attributes fluctuated significantly. Earth wizards, due to extensive research, had some leverage power-enhancing spells, but these were minor compared to elemental wizards. Elementals could multiply power by several folds, whereas strength increments were minimal: points of one, three, and five, with few ever achieving multiples.

Constitution, however, had its own merits. No tales recounted of elemental wizard apprentices facing mental power bottlenecks beyond 40, save for those who ascended to full wizards. Conversely, no tales described bottlenecks in Constitution.

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Constitution grew through passive evolution, devoid of upper limits or bottlenecks, breaking the boundary of levels. The so-called classes among subterranean dragon wizards, in terms of body training, were benchmarked against average combat power compared to elemental wizards, lacking distinct differences between levels.

For example, a high-stamina otherworldly creature might equate to between level 2 and 3 combat power, having strength surpassing a level 2 wizard but below a level 3. Yet, the gap between level 2 and level 3 wizards was significant.

Strength's advantage lies in the absence of thresholds or upper limits, leading to minor class distinctions. According to subterranean world wizard rules, a wizard with an attack strength threshold reaching 250 is considered a level 1 formal wizard, whereas 249 is insufficient—the combat strength difference between 249 and 250 is negligible. Generally, an 80~100 Constitution is needed to achieve a 250 attack level. (Strength attacks fluctuate greatly, but there are specific subterranean spells to enhance leverage.)

(This section introduces the concept of wizard attack levels, which will be elaborated on later to explain the true difference between formal elemental wizards and apprentices, beyond mere attack level counts.)

As for the downside of training Constitution...

Observing the infinite worlds, around 80% of creatures rely on passive evolution to enhance Constitution, yet the wizard world could enslave many such worlds...

Lastly, Vitality was 162296, seemingly a huge improvement from the previous 110157, yet toughened body defenses only reached 16 to 29—a bare minimum to meet the Pale Mask's attack immunity.

Nidhogg's journey to physique refinement was long and challenging.

Three days later, at the gates of Black Tower Wizard Academy, facing Thornspine Forest, Nidhogg looked at a man as brawny as an ox, clad in black leather armor with a massive axe on his back. His right hand seemed covered by a layer of tough black stone, exuding a strange metallic chill, glaring coldly at Nidhogg's approach.

Halting, Nidhogg glanced at the man and the familiar figure of Roman behind him, recognizing who he faced, and spoke in a cold tone: "Thunder Axe Gaide?"

"You are Nidhogg?" Gaide spoke, his mouth full of sharp teeth resembling a shark's maw, looking fierce and menacing—who knows what bloodline magic he had altered.

Nidhogg remained unmoved: "I am."

"Hmph!"

Gaide sneered, "Very well! You killed Harry Reid, showing no respect for my beloved Roman, even if Harry was in the wrong. It's not your place to punish! Killing Harry Reid, an outsider like you, has earned a spot on our four masters' kill list!"

"If that is meant as a threat, feel free," Nidhogg replied calmly, possessing the base strength and confidence akin to a wizard apprentice in the cold, competitive magic world, fearing no threats from equals.

"Fine!" Gaide's eyes flashed coldly, "Though I can't kill you here due to academy rules, you need a lesson!"

With a loud stomp, the ground cracked as Gaide vanished on the spot.

Nidhogg's pupils shrank, hair standing on end, his body instinctively defending. Following a surge of thunder power, the shield of the Pale Mask struggled and broke, a fist like polished granite smashed into Nidhogg's defending arms.

Boom!

Like a bolt from the blue, lightning flower exploded.

Amidst the chaotic lights, Nidhogg felt his body paralyze, his arm bones creaking, his face pale, retreating several steps. Gaide's strike exceeded 150 attack degrees, shattering the Pale Mask's highest defense.

So, this was the power of one of the academy's top four masters?

"This punch is Harry Reid's retribution, and this next punch is Roman's!" Gaide swung another fist as Nidhogg's pale face changed, gritting his teeth, and shouted loudly.

"Hah!"

Nidhogg summoned the indestructible flame armor at full strength. As Gaide's fist slammed into him, Nidhogg flew a dozen meters back, vomiting a mouthful of blood.

Simultaneously, an owl swooped down from the sky, perching on Nidhogg's shoulder, its eyes glowing with ghostly green light, staring coldly at Gaide, shrieking, "You are under Black Tower Wizard Academy's arrest. Report to the fifth floor of Black Tower immediately, or face death."

Nidhogg spat another mouthful of blood; after high-speed recovery through metamorphosis, he managed to stand, gazing at the owl with a complex expression, realizing the academy's enforcers weren't mere figures.

Gaide snorted coldly, retracting his fists, and under the owl's frigid eyes, turned arrogantly toward Black Tower's direction, nodding nonchalantly at Roman, appearing relaxed. Yet, he walked briskly, seemingly hiding the trembling hand beneath his sleeve.

Nidhogg wiped the blood from his mouth, noticing Gaide's robe's telltale signs, smirking. Someone so concerned with face—his indestructible flame wasn't mere decoration.

Later, the owl on Nidhogg's shoulder spread its wings, vanishing into the sky.