Half an hour of testing.

Klein already had a very detailed understanding of the upgraded Fire Ring.

The so-called control of flames referred to the fact that Klein could change the form of the flames.

For example, the previous Klein could only release fire elemental missiles.

Even with the Fire Ring, the flames that Klein released were nothing more than enhanced versions of fire elemental missiles.

As for the current Klein, he could change the shape of the flames at will and control its precision.

For example, if Klein released flames now, he could turn the shape of the flames into a net.

Or he could imitate the shape of a weapon, such as a fire knife, a rocket, a fire sword, a firearm, and so on.

Furthermore, Klein could even control the direction of the flames for a short period of time.

For example, previously, Klein could only fire fire elemental missiles in a straight line.

He could no longer control the fire elemental missiles he sent out.

But the current Klein was different. He could control the trajectory of the fire elemental missiles he sent out in a short period of time and in a short distance.

If the fire elemental missiles were too large, or if he released too many flames, it would be much more difficult for Klein to control them. However, he could probably make some minor adjustments to the trajectory.

This meant that Klein's current combat strength was much stronger than before.

He took a deep breath.

Klein opened the runic base.

At the same time, he opened the trading mall.

He placed the crystal gem on the shelves.

The crystal gem looked very beautiful, and it quickly attracted many people to buy it.

"My god, what kind of crystal gem is that, Big Brother Klein? It's simply too beautiful!"

"I've been in the catacombs world for so long, and I haven't seen such a beautiful thing in a long time. Sigh, it seems like I need a runic base to decorate."

"What kind of conditions do I need to obtain this gem?"

Klein's private messages were quickly flooded with people who wanted to buy the gems.

There were a total of five gems.

Klein didn't plan on keeping them.

Of the gemstones, only the one that increased his elemental control was useful. The rest weren't of any substantial help to Klein.

As for Klein's runic base, it could already be considered luxurious.

He didn't need this crystal to decorate it.

As for the others, they needed this crystal to add some fun to their boring lives.

Klein wasn't in a hurry to tell everyone the terms of the deal.

Instead, he exited the trading mall.

He planned to take a look at the blueprint for the advanced aircraft he had obtained previously.

Although Klein's aircraft could fly, he wasn't satisfied with its speed.

Therefore, when he obtained the blueprint for the advanced aircraft, Klein thought of upgrading the propeller to an advanced aircraft as soon as possible.

He opened the blueprint.

Klein looked at it carefully.

He realized that to upgrade to the advanced aircraft, he needed a silver shaft, five large screws, and an accelerator purifier.

And Klein didn't have any of those.

With that thought in mind, Klein opened the trading mall again.

He shouted on the world channel, "I need a silver shaft, five large screws, and an accelerator purifier. As long as you have one of them, you can trade with me and obtain a multicolored crystal."

Just as Klein finished his sentence, the world channel immediately exploded.

It was because the image of the crystal that Klein had uploaded was too beautiful.

Everyone would be attracted to it.

It instantly caused a wide discussion.

In addition, Klein had only uploaded the crystal image. As it didn't clearly indicate the terms of the transaction, there was a pre-heating, so the news had already spread to many groups.

Soon, Klein's background had once again triggered a large-scale private message transaction.

Klein quickly filtered the message and chose to check the private message that mentioned one of the conditions mentioned in the message.

Roger: "Mr. Klein, I happen to have three large screws here. May I exchange one crystal with you?"

Klein: "Sure."

The transaction was successful.

[System notification: Crystal-1]

[System notification: Large Screws+3]

After a while, Klein completed all the transactions one after another.

All five crystals were traded.

And he just happened to get all the materials needed to upgrade the aircraft.

The rest of the people who didn't get the crystals saw that the crystals had been sold, and they were all very disappointed.

Some of them had met the conditions that Klein had proposed, but they hadn't been selected because their private messages were too slow.

Klein had no choice but to send them a private message early next time.

After exiting the trading mall, Klein quickly took out his aircraft and placed the upgrade materials around the aircraft.

[Detected that the materials are sufficient. Use a silver shaft, five large screws, an accelerator purifier, and an advanced aircraft blueprint to upgrade the aircraft?]

"Yes."

Klein chose without hesitation.

[Upgrade successful!]

All the materials around the aircraft disappeared after a white light.

The appearance of the original aircraft had undergone a huge change.

It was a little bigger than before, and it looked a lot more handsome.

Klein put on the aircraft and began to fly in the air.

The speed was much faster, and the maneuverability is much more precise than before

After a few minutes of testing, Klein came to this conclusion.

Not only was the speed much faster, but it was also easier to control.

Such an improvement would allow Klein to deal with some troublesome fellows in the future. Not only could he sneak underground, but he could also fly directly into the air.

No matter what, it would be very difficult for the other party to do anything to Klein.

Klein looked around and prepared to enter the next catacombs.

A notification appeared in front of him once again.

[In the catacomb ahead, there is a gigantic Three-Winged Bird. It has three pairs of wings and is extremely fast. It can take your life in the blink of an eye. Before you even see it, it's already gone.]

[In the catacomb behind, there is a Psychedelic Butterfly. The psychedelic powder that it gives off will allow you to quickly fall asleep. When the prey falls asleep, it will cause you to never wake up again...]

[In the catacomb to the left, there is a Whack-a-Mole. The rats in there are extremely cunning, and there are many traps. Once you fall into a trap, you may never be able to come out again.]

[In the catacomb to the right, there's a group of Skull Monsters. They're very good at creating a terrifying atmosphere. Even an extremely powerful person would be scared to death.]

When Klein saw the notifications, he instantly had a choice.

He wanted to head to the catacomb ahead and see the Three-Winged Bird.

After all, he had just obtained an upgraded propeller. He really wanted to compete in speed with the other party.

If the other party's speed was even lower than his, wouldn't that mean that his advanced aircraft was very strong?

With this in mind, Klein directly entered the next catacomb.

'I'll meet the Three-Winged Bird!'