Nie Yan took out another third-order fire-系 crystal core. The Darkwing Dragon glanced at it and then turned its head away, seemingly not very interested in fire-系 crystal cores. However, it would still eat it, though the effect probably wouldn't be great.

It seemed that feeding a flying mount of a certain xi (system, lineage, family) required using crystal cores of that same xi. For the Darkwing Dragon, it needed to be fed dark-系 crystal cores to avoid wasting them.

Nie Yan tossed a dark-系 crystal core into the air.

The Darkwing Dragon quickly turned its head and snapped it up in its mouth like lightning, then crunched it and swallowed it.

Nie Yan could feel the Darkwing Dragon had grown a little stronger than before, but it was just a vague sense. He didn't know how much longer it would take for the Darkwing Dragon to advance.

After eating a crystal core, the Darkwing Dragon looked at Nie Yan expectantly, still wanting more.

Nie Yan took out another dark-系 crystal core and tossed it to the Darkwing Dragon.

The Darkwing Dragon crunched down on the crystal cores one after another. Since the Darkwing Dragon was a sixth-order creature, these first, second, and third-order crystal cores had very limited effects on it. However, if the quantity reached a certain level, the effect would be completely different. Nie Yan could feel the powerful dark aura emanating from the Darkwing Dragon, full of corrosive power. Any plants within a three-yard radius that came into contact with this dark aura immediately withered into dried grass.

The Darkwing Dragon burped, its stomach bulging. It had eaten at least a dozen of them since earlier.

After eating these crystal cores, the Darkwing Dragon dozed off. Seeing that it was about to fall asleep, Nie Yan put it back into the pet space.

Looking at the pet space, the Darkwing Dragon had already found a place to sleep, and a dense dark aura enveloped its body, completely wrapping it up.

The Darkwing Dragon had fallen asleep.

Nie Yan could feel the powerful force surging within it. He wondered what kind of changes would occur after it woke up.

Nie Yan withdrew his gaze. As he trained his various production skills and worked on the Saint Shadow Dancer job-change quest, he gradually reached the depths of the jungle. Looking into the distance, a magical and bizarre building, floating in the sky above the jungle, attracted his attention.

The building was very magnificent, completely floating, without any support. It was like a giant fortress that had experienced countless wars, scarred and battered, yet still very grand and spectacular.

Like Carol City in Greenland, it was a Sky City.

System: You have discovered the World's Heart.

Nie Yan was stunned when he saw this system notification. His heart shook violently. It was actually the World's Heart!

In the myths of the Curtis Codex, the World's Heart was the center of the world, floating in the sky above the Atlanta Continent, the place where the gods resided. However, after the Third Divine War, the World's Heart disappeared without a trace, never to be seen again.

Thus, the World's Heart was only mentioned in a few ancient books, and everyone regarded it as a vague and illusory existence.

Nie Yan intuitively felt that this World's Heart must be related to the Saint Shadow Dancer job-change quest, so he proceeded in the direction of the World's Heart.

The closer he got to the World's Heart, the stronger the monsters that spawned. Nie Yan's speed gradually slowed down. Looking up, he saw some black dots circling around the World's Heart. They were some kind of flying creatures. Although he had never encountered these flying creatures before, judging from their size, these flying creatures were of a very high rank, much stronger than his Darkwing Dragon.

About ten days later, Nie Yan completed quest progress 3, and another system notification sounded.

Quest Progress: Infiltrate the World's Heart and find the lost inheritance.

The quest had finally undergone some changes. He would go crazy if he continued to clear monsters. Third-order creatures were already very difficult to deal with, let alone fourth and fifth-order creatures! After completing the first three quest progresses, the subsequent quests were very different. However, infiltrating the World's Heart was much more difficult than the previous quest progresses.

Looking at the World's Heart in the distance, he would definitely need to use a flying mount to enter it. He looked down at the pet space. The Darkwing Dragon was still sleeping.

He sighed. He could only wait for the Darkwing Dragon to wake up. Nie Yan collected materials everywhere and continued to improve his various production skills. He checked the levels of his various production skills. Mechanic, Forging, and Scrollmaking had all reached Advanced, ready to advance to Master. In addition, his Alchemy skill had reached 52% of Master level, allowing him to create more potions.

As he learned more and more production skills, Nie Yan gained a new understanding of them. He suddenly had some amazing ideas. Could he make his own weapons?

Nie Yan obtained some iron essence. After forging and processing it, he slowly grinded it into a needle shape, about three inches long and roughly the thickness of a thumb. One end was ground very sharp, capable of easily piercing defenses. Then, using his Alchemist skill, he created bottles of blue poison and evenly smeared them on the needles.

This could also be considered a handy weapon that he could use in unexpected situations. Nie Yan thought for a moment, he could continue to enhance this thing. He used his Mechanic skill to give the iron needle a special treatment. Once this iron needle pierced into the enemy's body, it would form barbs that would hook the flesh, making it impossible to pull out. If it were forcibly pulled out, it would tear off a large chunk of meat.

This could be considered a bit of Nie Yan's cleverness. Just then, a system notification sounded.

System: You have invented a weapon. Attack Rating (Strength * 5 + 5000). Special Effect Rating: This weapon can cause 20% bleeding effect for ten seconds, and has a certain probability of crippling the opponent. Please name it.

Nie Yan looked at the properties of this weapon and was surprised by its effects. This attack was incredibly amazing, and it also came with bleeding and crippling. Nie Yan's Strength was around six thousand points. If he used it to attack an enemy, it would deal more than thirty thousand points of damage, and at the same time cause more than sixty thousand points of bleeding damage. It was simply terrifying.

What should he name this thing?

Nie Yan pondered for a moment, then decided to call it Bone Spike.

System: Naming successful.

System: You have successfully invented and created a Bone Spike. Forging and Mechanic each gain 500 skill proficiency.

Two beams of white light lit up on Nie Yan's body. It was the sound of leveling up! Nie Yan opened the skill list, and Forging and Mechanic had both been promoted to Master level. He hadn't expected to gain so much skill proficiency at once!

The skill proficiency was increasing so quickly! Nie Yan continued to make a second Bone Spike, but this time Forging and Mechanic only gained 5 skill proficiency each. It seemed that only when inventing a new weapon would he gain so much skill proficiency at once.

Even so, making Bone Spikes gave much more skill proficiency than making ordinary weapons, and it could improve both Forging and Mechanic skills at the same time, which was obviously more worthwhile.

Nie Yan finally realized how useful it was to learn all the production skills!

Ordinary players would generally only have one production skill. Even if they raised it to a very high level, they could only produce various items according to blueprints and recipes. It was impossible for them to independently develop and create a high-level item like Nie Yan, because generally high-level items required the assistance of at least two or more techniques. Even just mixing and making new potions was not something that could be done casually. It also required the assistance of other production professions, such as making special containers and so on.

The Bone Spike's power exceeded Nie Yan's expectations. In the future, it could be used as a powerful auxiliary weapon. In a few days, all his production skills would reach Master level. At that time, he could independently develop more things and use these special items to make himself even stronger.

Just as he was pondering, a violent fluctuation came from the pet space, and a powerful dark energy filled the entire pet space, overflowing from it.

What happened? Nie Yan was shocked and looked into the pet space. He saw a powerful dark force being released from the Darkwing Dragon's body. It stood up, its size a little bigger than before, and its body was covered with a layer of gray-black scales, densely covering the Darkwing Dragon's entire body, like a layer of armor protecting the Darkwing Dragon, reflecting a black, crystalline luster.

The Darkwing Dragon's wings were more powerful than before, and its strong body gave people a feeling of unparalleled strength.

Nie Yan glanced at the Darkwing Dragon's attributes. All attributes had increased by at least 30%. The Darkwing Dragon was not far from advancing, just a little bit more. If he continued to feed the Darkwing Dragon crystal cores, it might advance to seventh order before long. If it could advance to seventh order, its strength would increase several times.

Currently, the highest-order flying mount owned by other players was only fourth-order. With a difference of more than three orders, Nie Yan's Darkwing Dragon could easily crush all their flying mounts.

The Darkwing Dragon had finally woken up. It couldn't continue to eat crystal cores for a short time. Nie Yan looked at the World's Heart. He was going to ride the Darkwing Dragon up there!

Nie Yan prepared himself, making more than fifty Bone Spikes and a large number of Master-level instant recovery potions. He also prepared some high-level bandages. After making thorough preparations, he summoned the Darkwing Dragon.

The Darkwing Dragon appeared in the open space in front of him, and a powerful aura swept out. All the plants within a ten-yard radius were instantly drained of life, withering in a moment.

Nie Yan looked up and found that the Darkwing Dragon's height had reached five yards, and its metallic scales were almost indestructible, giving people a sense of heavy oppression.

Nie Yan straddled the Darkwing Dragon's back. The Darkwing Dragon flapped its wings and soared into the air, rising dozens of yards at once.