"-I removed the demonic energy from the heart but kept the venomous properties intact. You mentioned having poison resistance, so this will actually help build up your tolerance," Derek explained, his voice filled with exhaustion.

After spending half a day laboring intensely, he looked utterly worn out, as though he’d competed in back-to-back triathlons. Yet, despite his fatigue, a spark of life lingered in his eyes.

"The medicinal energy is too potent to blend evenly, so I also prepared three separate elixirs infused with water, earth, and wood qi. You’ll need to consume them in sequence."

"...Thank you," Ihan responded simply, acknowledging Derek's effort with a plain expression of gratitude. He could have launched into a lengthy speech to convey his appreciation, but that wasn't Ihan's style, and Derek would probably find it uncomfortable anyway.

With a subtle smile, Derek replied, "You’re welcome. I’ll take care of the rest… just give me a moment..."

Thud.

Before he could finish, he collapsed right where he stood.

"Looks like he might need the medicine more than me," Ihan muttered, catching Derek and laying him down on a hammock tucked into a corner.

Then, Ihan turned his attention to the vials of medicine lined up on the desk.

Glimmer.

"They’re pretty extravagant," he murmured, his voice neutral, though his eyes held undeniable surprise.

He had expected a straightforward refinement, but what Derek had produced was far beyond his expectations. Anyone could tell at a glance that these were supreme elixirs.

Despite being mere potions, a hazy aura rose from them. The three elixirs Derek had told him to take shone with colors of water, gold, and green, like iridescent pearls, looking as though they would melt the moment they touched his mouth.

"Water to nourish earth, earth to cultivate wood, strengthening the body’s defenses… Was Derek studying traditional medicine in a past life?"

The elixirs seemed to form a harmonious blend reminiscent of the five elements, their potency beyond ordinary comprehension. But even these extraordinary concoctions paled in comparison to the final potion.

"This… this isn’t just an elixir. It’s an infernal concoction."

He brought the vial to his nose.

If a radiant red sapphire could melt like liquid, it would look something like this. The vibrant red fluid glowed like fluorescent ink, and he couldn’t help but wonder if it was even safe for human consumption.

But—

“This one first, right?”

Without hesitation, Ihan drank it. The potion held Derek’s full dedication; the least he could do was consume it with due respect.

‘Not a drop left behind.’

He downed the three elixirs. Contrary to his expectations, they didn’t dissolve in his mouth; only as they slid down his throat did he feel the impact.

Boom!

“!!!”

An intense shock coursed through his entire body, unlike anything he had felt before. There was no explosion, but the sensation was powerful enough to feel as though one had erupted within him.

‘It feels like it’s drawing out all my internal energy.’

The three elixirs not only drew power from each other to amplify their presence but also devoured his energy, including the vitality he had painstakingly regained through those painful healing sessions with the priestess. Someone might have wondered if this was an attempt at poisoning, given the sensation of his life being drained.

Though he felt an overwhelming urge to expel the potion, a voice in the back of his mind whispered—

‘Maybe I should let it do its thing…?’

Ihan decided to let the elixirs continue consuming his energy until he felt his life force dwindle precariously low. He trusted that So-Shim had no intention of harming him, and besides, the energy didn’t seem life-threatening. Strangely, as the elixirs absorbed his vitality, he felt his body becoming lighter in a different sense.

It was as if unnecessary, residual energy—things he could do without—were being purged from within, as though the elixirs were forcing his body to empty itself to make room for something greater.

For several long minutes, he let the three elixirs work their way through his system, sapping his energy at their whim.

“...Ugh.”

Eventually, Ihan lost even the strength to speak, and his vision blurred as dizziness overtook him. He felt ready to pass out.

If there had been a mirror, he might have been horrified by his appearance. His once powerful frame now looked gaunt, almost skeletal. Thankfully, he couldn’t see himself in his current state, with dimmed vision and no mirror nearby.

Without being able to assess his own appearance, Ihan reached for the vial containing the red liquid with a trembling hand.

Even though it weighed less than 250 grams, lifting it felt like a monumental task. Pain, exhaustion, hunger, and thirst all clawed at him, his body wracked with conflicting desires to eat and sleep simultaneously.

If his sexual desire hadn’t been sealed, it was likely his behavior would have taken an embarrassing turn as well.

In this state, Ihan relied solely on sheer willpower to keep himself in control, restraining all urges and discomfort.

"Shut up. Quiet… quiet!"

He commanded his uncooperative body to obey him. He willed every part of himself to follow his intent, demanding complete submission.

Gulp.

Ihan forced the red liquid into his mouth.

Gritting his teeth.

It felt less like drinking and more like chewing. Although he was downing a liquid, it writhed in his mouth, like eating a stubbornly squirming octopus or tough pork skin.

“──”

But Ihan didn’t let a single drop escape his lips. He kept chewing and swallowing, determined not to let any of it go to waste.

Finally, he swallowed it all.

And that’s when the real ordeal began.

Boom—!

Crackle.

A shocking jolt swept through his body like an electric current, as though a minuscule person had entered his stomach and was furiously pounding on his insides with a massive war hammer.

The pain was insane, flipping him over, breaking through any attempt to suppress his screams. He had no energy to shout, and his vision blurred as if he were on the verge of passing out.

It felt like his entire world was closing in on him, as if he were experiencing childbirth—if he could imagine such a thing.

‘Wait… I’m a man.’

The thought passed through his mind, leaving him slightly incredulous, but he realized that if he could still think, he wasn’t in danger of dying just yet.

The energy from the three elixirs he had taken earlier seemed to be curbing the monstrous effects of the heart’s essence.

‘Ha! So, this is what they meant by potency?’

He’d heard that the heart’s essence was powerful, and that was why the three elixirs were necessary. But this was beyond mere potency.

Completely overwhelmed by the potency of the Demon King’s Heart, Ihan’s senses faded. Without the first three elixirs protecting his stomach, he might have already succumbed to the pain.

‘Honestly… maybe passing out would be better.’

He let out a bitter chuckle but quickly decided against giving in. He needed to know precisely what was happening to his body.

‘Fine… Let’s see who wins.’

He bit down on his tongue, drawing blood. The metallic taste grounded him, and the pain brought him back to awareness.

With a deep breath, Ihan forced himself into motion.

Step, step, step.

He began stepping forward, as if shadowboxing, his fists flying in the air.

Although he felt devoid of energy, his body frail and wracked with exhaustion, he found that moving alleviated the mental strain. Though any observer might have seen this as pure brute force, to Ihan, it was a matter of survival.

Whoosh!

He threw his fists, again and again.

At first, the movements were sluggish; moving his body itself was painful. But Ihan remained stubborn, refusing to give in. His punches started gaining speed as he pushed his limits.

The once-weak punches grew sharper and faster.

Whoosh, whoosh!

Before long, Ihan’s entire body was radiating strength.

He’d realized yesterday that power could emerge from gentleness. Power resided everywhere; even a body drained to the last ounce could summon it with the right approach.

Little by little, his punches took on a threatening sharpness, like a nail driven in with precision. He had achieved no grand enlightenment, only fought to endure the pain and the overwhelming power of the elixirs.

And this desperate struggle—

Creak!

—gradually bore fruit as he began to absorb the elixir’s potency. What should have taken all day to complete was instead being absorbed in mere hours as Ihan forced himself to adapt.

“...”

At some point, Ihan entered a trance-like state, his movements mechanical, as if his body moved on pure will.

Lost in this state, he missed the subtle yet remarkable transformation taking place within him.

Hiss.

Steam began to rise from his skin, purging his body of toxins accumulated from the unknown potions forced upon him by a wizard in his youth or the poison from his battle-hardened body. Sweat poured out of him as his once-heavy fatigue drained away.

Bang! Bang!

And the essence of the elixirs went a step further, causing his emaciated frame to regain its muscle mass. This time, however, his muscles did not just grow in bulk; they gained a resilient elasticity, a spring-like quality.

He was surpassing his previous limits, his body advancing into newfound resilience.

This was nothing short of a miraculous encounter.

Yet, to attribute his progress solely to the elixirs would do a disservice to his tenacity.

When Derek finally came to about ten minutes later, he could hardly believe his eyes.

There was the matter of the walls that seemed on the verge of being destroyed…

“Did you just… take it all at once? Without waiting for me to explain the order?”

“…”

“I told you before I passed out that you had to follow the sequence, didn’t I? And weren’t you in agony? Taking them out of order is like pouring oil on fire!”

“…”

“If you’d tried to endure that pain on your own, you could’ve ended up seriously hurt…”

“…Mm.”

“Was it… very painful?”

“Ahem.”

Ihan stared off into the distance. Despite being underground, he found himself gazing at imaginary mountains.

And he thought to himself,

‘That… that really did hurt like hell.’

Confirming once again why people say that a lack of knowledge only makes you suffer more, Ihan couldn’t help but take the lesson to heart.