Upon hearing the system's voice, Lin Feng was immediately overjoyed.

Next, I looked at the system panel.

Upgrading a cultivation technique to Earth-level requires one million gold coins, which is equivalent to ten thousand stones.

He now has a total of five or six hundred thousand shi (a unit of dry measure).

So he didn't hesitate to upgrade immediately.

"bite!"

"Congratulations, host, for successfully upgrading your cultivation technique to the Earth-level by spending 10,000 Yuan Stones!"

The system's voice immediately sounded.

boom!

As soon as his cultivation technique was upgraded, Lin Feng immediately felt the power within his body increase exponentially!

Originally, the thirty-six drops of liquid true essence in my dantian suddenly increased to seventy-two drops, doubling in size!

And his strength increased many times over!

"As expected of a high-level cultivation technique, it truly did not disappoint me!"

Lin Feng clenched his fists, feeling the immense power surging within him, and couldn't help but smile excitedly.

He believed that with his current strength, if he were to face that refined man in yellow robes again, he could easily kill him instantly!

Looking at the system panel again, he could finally continue upgrading his cultivation technique after it reached the Earth level.

So he immediately chose to upgrade.

"bite!"

"Congratulations, host, for spending 100,000 gold stones to successfully advance your cultivation to the first level of the Grandmaster Realm!"

The system's voice sounded again.

boom!

The moment his cultivation broke through to the Grandmaster realm, the power within Lin Feng's body increased exponentially once again.

In the dantian, the original seventy-two drops of liquid true essence suddenly condensed into a perfectly round and large golden martial pill!

"Huh? The size of my martial core seems to be much larger than the martial core recorded in the Earth-level cultivation technique of the City Lord's Mansion..."

Lin Feng was quite surprised when he looked inward at the golden martial core in his dantian.

According to the records in the Earth-level cultivation technique of the City Lord's Mansion, the martial core condensed by those who cultivate this technique is only about three inches in diameter.

However, the martial core he condensed was a full five inches in diameter!

"The Earth-level cultivation technique in the City Lord's Mansion is only at the initial Earth-level stage. Five inches should be the size of a martial core that can only be condensed by a mid-Earth-level or even high-Earth-level cultivation technique... It seems that after my cultivation technique is upgraded to Earth-level, it is at least comparable to a mid-Earth-level technique..."

Lin Feng thought excitedly.

Then, looking at the system panel, it was found that it would take 300,000 yuan stones to raise one's cultivation to the second level of the Grandmaster realm.

So he immediately chose to continue upgrading.

"bite!"

Congratulations, host, for successfully advancing your cultivation to the second level of the Grandmaster realm by spending 300,000 gold stones!

The system's voice sounded again.

As his cultivation level improved, Lin Feng's internal power surged once again.

"The next upgrade requires 500,000 gold stones, and I only have 100,000 left. It's not enough again. This money is really flowing out like water..."

After glancing at the upgrade costs, Lin Feng couldn't help but smile helplessly.

"Brother Lin, I found a low-level sword technique inside. I'll give it to you as well!"

At this moment, Shen Chuan suddenly emerged from the depths of the secret chamber, holding a beautiful ancient book made of animal hide, which he generously handed to Lin Feng.

"Earth-level sword technique? Thanks, brother!"

Lin Feng's eyes lit up. Without being polite to Shen Chuan, he took it and began to examine it. "The Nine Heavens Thunder Sword has nine levels. The first level allows one sword to unleash nine bolts of lightning. When the ninth level is perfected, one sword can unleash eighty-one bolts of lightning. Its power is comparable to a mid-level Earth-grade martial skill!"

"bite!"

"Congratulations, host, you have obtained a Tier 1 martial skill. Would you like to spend 10,000 gold stones to learn it?"

The system's voice immediately rang out as soon as I finished reading the introduction of this sword technique.

"Learn! Learn right now!"

Lin Feng made the decision without hesitation.

"bite!"

"Congratulations, host, for spending 10,000 gold stones to completely master the Nine Heavens Thunder Sword!"

The system's voice sounded again.

At the same time, Lin Feng also mastered this sword technique out of thin air.

Moreover, the "Nine Heavens Thunder Sword" he mastered was even more powerful than the martial arts manuals recorded, capable of unleashing a full three hundred and sixty sword energies with a single strike!

Its power surpasses that of a mid-level Earth-grade martial skill and is comparable to a high-level Earth-grade martial skill!

Next, look at the system panel. Spend another 10,000 Yuan Stones to upgrade the "Layered Wave Sword Technique" to Earth level!

So, Lin Feng didn't hesitate to spend another 10,000 Yuan Stones to upgrade the "Layered Wave Sword Technique" to the Earth level!

After the upgrade, the power of "Layered Wave Sword" has also been greatly increased.

The previous "Layered Wave Sword" could unleash thirty-six giant waves of sword energy with a single strike!

The current "Stacked Wave Sword" can unleash seventy-two giant waves of sword energy with a single strike, and its power is comparable to a mid-level Earth-grade martial skill!

"Brother Lin, you are free to look at all the martial arts techniques and skills in this secret room, including various classic texts and secrets. No need to rush, take your time. I'll go check on my father first!"

Shen Chuan, who was standing next to him, was completely unaware that Lin Feng had undergone a transformation. Suddenly, he said with a solemn expression.

"Alright, then I won't stand on ceremony with you, brother. You go ahead and get busy!"

Lin Feng smiled and nodded.

The treasured books in this secret chamber are even more profound than the entire Doujian Sect's foundation. Besides cultivation techniques and martial arts skills, Lin Feng is also very interested in other kinds of books. If Shen Chuan doesn't mind, he really wants to read more of them in order to broaden his horizons.

"Don't mention it! You saved my life, my life belongs to you! If you want it, I'd even give you the position of city lord, no problem at all!"

Shen Chuan said with a sincere and grateful expression.

"No need for that. You go ahead and do your work. Find out what's wrong with your uncle. If there's anything I can do to help, let me know as soon as possible. I'll do everything I can to help!"

Lin Feng shook his head and smiled, speaking very sincerely.

"Um!"

Shen Chuan nodded and then left the secret room.

Lin Feng, on the other hand, browsed with great interest the various precious books treasured in the secret room.

"Weapon forging techniques? The Eighteen Fists of Wind Breaking? Mastering them completely will make you a fourth-grade weapon forger? Doesn't that mean you can directly forge Earth-grade weapons that surpass even Xuan-grade weapons?"

Lin Feng picked up a weapon-refining manual and began to read it thoughtfully. "I've heard that weapon refiners are in high demand. They can earn a lot of money from a single Xuan weapon, let alone an Di weapon... If I could become a weapon refiner, I might not have to rely solely on system rebates to earn money and level up in the future..."

"bite!"

"Host has been detected to have obtained a Grade-Earth Refining Manual. Do you wish to spend 10,000 Yuan Stones to learn it?"

The system's voice suddenly rang in Lin Feng's mind.

"Ten thousand yuan is all it takes to learn? That's cheap! I'll learn!"

Lin Feng was overjoyed and immediately chose to study without hesitation.

"bite!"

"Congratulations, host, for successfully learning the Earth-level weapon refining technique by spending 10,000 gold stones!"

The system's voice sounded again.

At the same time, Lin Feng also directly mastered this weapon-refining technique and became a fourth-grade weapon refiner!