At this time, Xu Xin's watch vibrated again. It was Li Wenxi calling.

Although it is not dawn yet, she is about to take a large group out to mine.

"How's it going over there? I saw in the explorers that they said you've gone down and found some mechanism. It's not too dangerous, is it?" Li Wenxi was a little worried.

"Don't worry, it's safe for us to come down together to explore this time." Xu Xin said with a smile.

"Well, you must be careful then."

Xu Xin was observing the surroundings while chatting casually with Li Wenxi.

She said that she planned not only to dig iron ore today, but also to take people to dig saltpeter and black gold mines.

Indeed, saltpeter is now needed to make explosive crossbows and heavy crossbows, and black gold ore is also the raw material for universal alchemical materials. These two ores are also indispensable.

"This is a huge burden for you. Why don't you let my beloved concubine and those two little guys help you? I don't know if they can enjoy your 100-fold explosion rate bonus." Xu Xin suggested.

"Right!" Li Wenxi also thought of this. "Well, I'll take them to try mining this time!"

Aifei's mining speed is very fast, but without a high explosion rate, it may reduce the total output of a mine.

However, it doesn't matter. The world is so big, Li Wenxi can explore for minerals, and he can also make convenient things like portals. The total production volume of a mineral does not need to be considered at this stage.

At this stage, the priority is to improve mining efficiency.

"Okay, I'm leaving too, so you have to be careful too."

After hanging up the call, Xu Xin had already walked around the iron room.

The smooth iron walls and floors do not feel cold to the touch, but instead give people a subtle warmth.

That's right, he didn't notice it when he touched the ground just now, but now he found that the walls and floors here were actually a little warm.

Probably, the temperature is around 20 degrees.

The heat radiating from the iron plates on all sides makes the inside of this iron room relatively warm.

Compared to the single-digit temperature outside, the temperature here is more suitable.

Moreover, it is worth noting that the gaps between the walls and the iron plates in this iron room are not seamless.

Instead, a very tiny gap is left.

This made Xu Xin slightly alert.

He knew exactly what this gap was used for.

Release the red mist!

That’s right, he was forced to climb up and escape in a panic because of the red mist released from this gap.

Since there is such a gap in this room, it means that red mist will also be released here.

Lou Feier had mentioned before that there was a faint smell of red mist here.

He couldn't smell it.

"The sixth one has been found!" Lou Feier's surprised voice came over.

"Hmm!" Coco also let out a somewhat complacent cry.

"Good job Coco!"

“Oh my!”

Xu Xin walked over.

At this time, Lou Feier was standing on a sinking iron brick. When she saw Xu Xin coming over, she walked out before the brick sank into place.

Then, she took out a stone from her backpack and placed it on the brick, then nodded with satisfaction: "Done! I turned on all the gravity machines and placed a stone on each one."

Xu Xin looked around.

Sure enough, a green-level stone was placed on each of the square bricks, including the one he had stepped on before.

The green light emitted by these stones showed their location in front of Xu Xin.

"Not bad...eh?" Xu Xin said softly.

"What's wrong?" Lou Feier asked in surprise when she saw him frowning.

"The location of these gravity mechanisms seems to... symbolize something." Xu Xin observed and thought.

These six gravity mechanisms seemed to form a circle at equal distances on the six vertices of a hexagon.

Xu Xin walked to the middle of these gravity mechanisms and reached out to touch the floor.

There are no hints.

Perhaps, something will appear only after the mechanism is triggered?

"Hmm?" Coco ran to his side, tilted her head and looked at him, not understanding what he was doing.

Coco didn't find anything either.

It seems that he was overthinking it.

"Let's talk about it after they come down." Xu Xin picked up Keke, stood up, and looked at Lou Feier. "Where is the specific location of the thing that can make you stronger that you mentioned?"

"Hmm... I feel like it should be underground... Yes! It's underground." Lou Feier nodded with certainty.

Underground?

"Perhaps, this mechanism is to open the passage into the underground?" Lou Feier guessed.

"Well, it's very likely." Xu Xin nodded.

At this moment, a faint sound came from the passage, which was picked up by his enhanced hearing.

"They are coming down." Xu Xin came to the entrance and waited.

"Huh? How did you know? Did you hear it?" Lou Feier also walked over and looked up, but couldn't see anything.

The two waited for another three or four minutes.

"Here they come! They're coming down!" Lou Feier had been staring at the passage, and finally saw some figures.

Soon, the first person approached.

"Stay away!"

It was Wen Guixin's voice.

The two of them took two steps to the side, and Wen Guixin immediately jumped down from above and landed lightly on the ground.

Compared to Zeng Tao's way of hitting the ground with a "bang", Wen Guixin, who also has high combat power, is much lighter.

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