Ren entered the last door, but he almost exited in fear. A large white beast loitered inside the otherwise empty room.

It was a white lion. Not only did it possess a height of 3 meters, but its mane also glowed in an awe-inspiring manner. Compared to the young Ren, it resembled a giant.

While Ren studied the lion, it had also noticed Ren.

“Challenger, why did you choose this path?” Its fruity voice spoke a new language, one that Ren had never heard of before.

Even so, Ren felt a sense of familiarity with the language. It was almost as if he had encountered his long-forgotten native language. The magical abilities of Omnilingual Evolution astounded him.

“I’m not sure. A gut feeling?” Ren replied honestly. He felt a weird sense of familiarity from this weird lion.

“As expected.” The lion grinned and greeted Ren, “Welcome to the path of Forbidden Skills.”

‘Forbidden Skills? So, it wasn't an Elemental Conversion Technique? Not even a Bloodline Skill?’ Ren smiled depreciatingly.

“Do you know about the other doors?” He asked, curious about the options he had missed.

“Spirit Bonding, Magic Crafts, and Honing.” The lion replied in a matter-of-fact tone.

‘Spirit Bonding? That must be clone with the wolf. Magic Crafts… Whatever that is. How is it any different from Magic Arts? And this… Honing. Damn it! Why do I hear of this everywhere? What even is it?’

“Are you regretting your decision?” The lion said. It seemed intent on shooing Ren.

“Not really. I just don't know much about Forbidden Skills.” Ren answered. He didn’t doubt the strength of this path. At present, his strongest attack was a Forbidden Skill.

"Gahr! Your predecessor didn’t regret his choice. You won't regret it. I, the Lion Sage, shall be your teacher from today.” The lion reluctantly said.

“Predecessor?”

“You’ll meet him later. Introduce yourself.” The Lion Sage yawned.

“Ren.” Ren wondered if he'd regret his choice.

“Ren? Your names are growing weirder by the generations." The lion grumbled before continuing, "What do you know about Forbidden Skills?”

Ren reflected for a moment before summarizing Lena’s explanation.

“A Forbidden Skill gives its practitioner the power of a 'Honed Act' without going through the labor. It is accompanied by backlashes, ranging from injuries to death.”

The lion gaped. It blinked a couple of times.

“HAHAHAHAHA!!!” It rolled on its back, unable to control its laughter.

Ren awkwardly smiled at this scene.

'At least, this sage isn't grumpy anymore.' It took a minute for the lion to settle down. It wiped the tears on its eyes and asked.

“Who taught you this? Was it Kaero?” The lion asked after calming down.

'Kaero?' Ren's eyebrows rose in surprise. He did not expect to hear a familiar name in this place.

“Kaero! Come out! You win our bet!” The lion shouted.

A bright light flashed, and a teenager of about 13-14 years old appeared in the dark space. He possessed silver hair and pure black eyes.

‘He really looks like Sis Lena. If only his hair was black...’ Studying the new guest, Ren felt a vague sense of déjà vu.

“Teacher?” The newcomer stretched his body, seemingly having just woken up from his slumber.

'Are all Forbidden Skill Practitioners sleepyheads?' Ren wondered.

“You won the bet! I’m so proud of you! You managed to convince your homeland that Forbidden Skills are a shortcut to Honing. Your junior here believes your nonsense.” The lion laughed.

“Ren, let me introduce you to your Senior. This is Kaero… To be precise, this is an identical clone of Kaero. I created him when he completed the trial. The real Kaero has left the trial a long time back.”

Kaero smiled wryly and apologized.

“Junior, I’m truly sorry. I placed a nonsensical bet with my teacher. I didn’t think that my real self would act on it. I apologize.” He bowed.

“…You don’t have to apologize. I had forced Sis Lena to explain.” Ren avoided Kaero's gaze.

“Lena? How is she? Is Kana fine? What about Dad and Mom? And-” Hearing a familiar name, Kaero’s eyes brightened. Before he could bombard Ren with a storm of questions, the Lion Sage stopped him.

“Kaero! This isn’t the time for chatter. Your junior is working on a deadline. And did you forget your promise?”

Kaero’s shoulders slumped as his expression turned despondent. He smiled faintly and nodded.

“Good luck, junior! We’ll talk after you finish your test.” Waving his hand, he prepared to leave.

“Stop! Since you’re already here, give your junior a background on Forbidden Skills. I’ll lend you control over this room.”

Kaero’s eyebrows rose in surprise. He nodded and pointed above his head.

“Junior, energy exists in a myriad of forms. These are so many that an individual can't compile all of them. We, as living beings, interact with these forms of energy in many different ways."

A silhouette of a human appeared above Kaero. It resembled a shadow. Many colorful lines surrounded it. It picked a blue line and absorbed it. Its silhouette turned blue.

“Since we prefer characterization, we call these interactions and energies with various names like Magic Arts and Mana, Physical Arts and Tai.”

Other silhouettes appeared in the empty space. They picked lines of different colors, creating a colorful picture.

“However, all of these energies have one thing in common. They despise existing as free energy and they desire a body to enter. In the extreme case that there are no bodies, they will crystallize.” The lines of energy that did not enter humans formed solid crystals.

“And once a body is destroyed, the energy returns to its free state, completing the cycle.” Some of the crystals broke into lines. The process of formation and breaking of crystals occurred in a dynamic equilibrium.

“We call this the Law of Energy Interaction. ‘Energy in its Free State tends to interact or crystallize, provided it isn’t in equilibrium with its Crystal State.’ This is just a roundabout way of saying that we can interact with energy and thus become, Practitioners. Accept this definition with a pinch of salt.” Kaero sighed and continued.

“For example, the branch of Magic Arts involves the channeling of mana while the branch of Physical Arts involves the absorption and conversion of Natural Energy into Physical Energy. These forms of energy are inclined to interact with Practitioners, provided the Practitioners aren’t disabled in any way.”

Ren hid his sadness with a smile. Kaero’s explanation gave him insight as to why he could use his Qi despite being a ‘cripple’. Unfortunately, he couldn’t convert it to Physical Energy.

“The other myriad paths also work in similar patterns. Forbidden Skills depend on a specific energy called Void Energy or Kyo. Now, are you curious about the significance of Void Energy?”

Ren nodded. The silhouettes and Kaero’s explanation captivated him. More than anything else, it gave him a much-needed understanding of Energy in general. Even the books weren’t concise in their explanations.

Kaero’s expression turned grim. A new line appeared above his head… A black line. Ren barely noticed it as it blended perfectly into its surroundings.

“Void Energy is the exception! I’m not boasting! It doesn’t obey the Law of Energy Interaction. It almost exclusively exists in an inert state.”

Many silhouettes tried to absorb the black line, but they failed. The black line floated, like an ethereal, untouchable dragon.

“To interact with Void Energy, a Kyo Practitioner has to meet one out of three criteria. Otherwise, an interaction is impossible, irrespective of whatever they do. This has held true for eons.”

‘Three criteria? Could they provide some clues to my past?’ Ren's eyes gleamed. He hoped that Kaero would elaborate on this topic. Unfortunately, Kaero skipped ahead with his lecture.

“Even so, Kyo Practitioners couldn’t absorb or channel Void Energy. Instead, the Void Energy temporarily touched their bodies before reverting to its inert nature.”

The black line entered a silhouette. The silhouette cracked, purple blood dripped down its body.

“In return, it provides extraordinary strength to the Practitioner. This is a basic Forbidden Skill. Regrettably, Kyo harms everything it touches. Backlashes are unavoidable.”

The bleeding silhouette punched another silhouette, blasting it to shreds. But the backlash destroyed its fist. Purple blood spurted out of its wrist.

“This is the basics of Forbidden Skills. Our goal as Kyo Practitioners is to optimize our yield while suffering minimal backlashes. There is much more to this branch, but I’ll stop for now. Still, before you take your test, I have to warn you.” Kaero took a deep breath.

“Interactions with Void Energy are extremely dangerous. Kyo Practitioners are destined for death!" Kaero's eyes glazed over as he continued, "They can never attain immortality. With physical arts, magic, and the like, there is always hope and potential for long, sustainable lives. That is why I’ll give you an option. If you wish to return, the door is free.”

Ren closed his eyes, digesting all the information. Confirming his choice, he answered.

“Immortality is the least of my concerns. I desire the strength to succeed in this trial.” His amber eyes gleamed with resolve.

“Good, I hope you can pass your test.” Kaero grinned. He turned to the sleeping lion, “Teacher, he's ready.”

“Done already? Why don’t you conduct the test?” The lion yawned. Kaero smiled wryly and prepared to leave when Ren stopped him.

“Wait, you didn’t mention anything about the three criteria!” Ren shouted.

Kaero’s eyebrows creased. He thought for a moment before a nefarious smile crept up his face.

“If you’re interested, meet me after you finish the test. That is if you don’t die here.” Kaero winked and disappeared.

“Gahr! Lazy brat!” The lion stretched. Turning to Ren, it spoke.

“Ren, I’m not going to waste any more words. Your first test is simple. Evade.” Towards the end, the lion's voice changed to a playful tone.

Ren felt a foreboding. Before he could ask another question…

Bam!

Ren collapsed onto the ground. He hurried onto his feet and took a defensive stance.

‘What was that?! An invisible punch?’ He panicked.

Bam! The blow landed on his abdomen, forcing him onto his knees.

Cough! He coughed a mouthful of blood.

Bam!

Before he could recover, another blow landed on his left ear. It ravaged the delicate internals of his ear. Ren felt the blood on his ears, and his expression turned surreal.

“Learn to evade. Otherwise, you will die.” The lion calmly laughed.

Ren barely heard the lion’s words. His heart pounded in fear. In desperation, he protected his face with his hands, his vision shaky.

Bam! Crack! Bam! Crack!

As he focused on protecting his face, the invisible blows targeted his ribcage. They increased in frequency and their strength increased with each hit.

Ren crouched on the ground, frantically reducing his size. His face contorted with pain and despair. However, the attacks showed no mercy.

Ren realized that he couldn’t continue. Soon, the blows would destroy his last defense and kill him. He had to defeat the invisible assailant before the assailant killed him.

Bam!

‘Now!’ With all his energy, Ren punched in the direction of the last blow.

Whoosh! …Bam!

His punch landed nowhere but the next invisible attack scraped his right ear, crippling his hearing.

Ren wobbled like a drunkard. He threw caution into the air as his punches flew in all directions.

Bam!

“Aargh!” The next blow landed on his right eye.

He punched forward, but his fist hit nothing.

‘What creature is this? This is unfair!’ Ren screamed internally. The threat of death kept him focused. Otherwise, he would've surrendered.

“Try to use your- Oh, he’s deaf. Maybe it’s too late…” The lion smirked at Ren’s dying struggle.

"He's probably another one of those lambs. Gahr, how many is it now? Over 5000? Gnah, I'm sure it’s more. Shouldn't have stopped counting at 2000. Please don’t waste my time and die already. I want to sleep." The Lion Sage yawned.

Ren used his right palm to defend his remaining eye, his last refuge. But the blows ruthlessly rained on his body, further reducing his abysmal chances of survival.

‘Why? Why can’t I hit it? Is it untouchable? Wait! Untouchable! Void Energy is untouchable. Is this Void Energy?!' Remembering Kaero's explanation, he nearly surrendered in despair.

'How am I supposed to defend against an untouchable force? Ahhh… I must find a solution!’

Despite fighting with a single eye, Ren did not abandon his hope. He knew that there had to be some method to fight back. Otherwise, Kaero and the lion wouldn’t have recommended this ‘test’.

Bam! Crack!

‘Argh… Think! Think! What am I missing? NO!'

Cough! He coughed again, nearly choked on his own blood.

As time passed, he felt light-headed as his consciousness began to tip on the edge. The threat of death materialized as he forced himself to recollect everything he had heard.

'Remember…’ Kaero’s explanation continuously played in his mind.

‘Void Energy… Forbidden Skills… Untouchable… Inert State… Ah!’

A weak smile crept up Ren’s face. He had thought of a plausible solution.