If it was original, Yun Lei would not dare to provoke this earth current. Because the power of this earth current itself has even surpassed the wooden ghost face, if it is not operated properly, even if Yun Lei is the master of thunder and lightning, but in the face of this absolutely vast power, he is not completely sure, and he retreats with his whole body.

However, now that there is this Nanming Lihuo and the space gourd that has been advanced to an immortal weapon, as well as a few top-level treasures with a wooden ghost face, it is not a problem to only provoke a trace of the earth's electricity.

And the energy of this earth current itself is indeed majestic and vast. Moreover, the quality is extremely high.

Even if Yun Lei had the need to expand his meridians, absorb energy, and transform his life, after absorbing this earth current for a while, he would also obtain enough energy for his advancement. Even, there is a feeling of being overwhelmed!

This earth current is surging, and its quality is closer to spiritual power than other ordinary thunderbolts. After only circulating once in the meridians of the cloud thunder, it was smoothly refined by the cloud thunder. It turns into a small spherical electricity, like a pearl.

After this advanced stage of the Dan Formation, the meridians of Yunlei did not expand much, but the spherical electricity that circulated in the meridians, like beads, and its own energy structure was once again promoted and transformed. The energy of each spherical electricity, under the same total amount, collapsed towards the center, and the volume became much smaller.

According to the proportion of the volume, the size of a spherical electricity with the same energy, if it is a ping pong ball, then, now, under the condition that the total amount of energy remains the same, the volume of a spherical electricity is only the size of a cherry.

While the volume of spherical electricity decreases, the amount of spherical electricity in the cloud and thunder meridians naturally increases!

The total amount of energy that oneself retains and grasps has naturally increased! And it has increased exponentially, and the volume of this spherical electricity has increased, and the total amount of thunder and lightning spiritual power mastered by the cloud and thunder itself has increased!

Rao Ya slowly woke up after the normal temperature of Nanming Lihuo in the cloud thunder that hit his flesh and blood, and exhausted the Yin Spiritual Qi of his body, allowing his withered flesh and blood to regain his vitality.

When he woke up, he saw thick arcs of electricity, catapulting out of the magma, and submerged into Yun Lei's body.

And the whole body of Yun Lei also flickered from time to time with slender and uncertain lightning arcs.

Yun Lei, who was in the midst of thunder and lightning in the sky, had a wooden ghost face on his face, held a gourd with a luster, warm and jade-like luster, but unknown material, and a huge hammer full of thunder light on his left and right. There was a cluster of flames burning overhead, just floating in the air, standing in the air, like a thunder god from ancient times.

With an indescribable aura of desolation. Whether it is the space gourd, the hammer of Thor, the wooden ghost face, or the Nanming Lihuo, its origin is hundreds of millions or even billions of years ago!

At this moment, the aura on Yun Lei's body suddenly changed. The thunderbolt arc of the body suddenly converged, as if it had never existed, and suddenly disappeared. Then, a breath of breath was released from Yun Lei's body.

Rao Ya clearly felt that today's Yunlei had stepped into the realm of the middle stage of Yudan.

Rao Ya and Yun Lei looked at each other and smiled. In the past few months, Yun Lei and Rao Ya have gone through all kinds of catastrophes, and now everything has finally calmed down. Rao Ya hugged Yun Lei and didn't want to let go of his hand anymore. The same is true for clouds and thunders.

But now, it's time for them to go back.

If Yun Lei and Rao Ya are in the outside world now, even if the two of them don't know the specific spatial coordinates where they are now. Cloud Thunder can also teleport all the way back with a vague sense. It didn't take much time at all.

And in this underground world, Yun Lei can't use this method. If one teleportes badly, it will teleport into the mountain. A hill about 100 meters high can reach 10 million tons of mass. The Tibetan Plateau in China is full of mountains thousands of meters high, and the weight of each mountain must be counted in 100 million tons, or even 1 billion tons.

If Yun Lei and Rao Ya were accidentally teleported into this mountain, even if Yun Lei's current cultivation broke through the bottleneck and had a few heavy treasures to protect himself, he would still be worried about falling.

Therefore, if Yun Lei and Rao Ya want to leave this underground space, they still have to find a natural exit.

This area can reach more than one million square kilometers of underground space, and there is definitely more than one exit to the outside world!

However, most of these exits are impassable for humans. Among them, there is either earth-fire magma flowing, or it is rugged and narrow, flowing with turbulent water. Moreover, it is also very narrow, not to mention that people can't get through the narrow places, even cats can't get by!

Yun Lei took Rao Ya to explore this underground world, and it took about three or five days. All the exits from the underground world to the outside world have been explored. There was even a trace of the Prussian expedition team left by the members of the Prussian expedition next to a river where the hot springs flowed.

These traces are scattered bones and relics. It seems that these members of the Prussian scientific expedition died in this hot spring like a chemical agent of three acids and two alkalis. On all the relics, there are traces of acid and alkali corrosion. Many are no longer recognizable.

With Yun Lei's current supernatural powers, it is not impossible to use these natural narrow passages to forcibly open a path to the outside world. However, in this underground space, whether it is the space environment, minerals, and biological resources, it is extremely rich and fragile. Yun Lei didn't want these things to be destroyed.

These narrow passages are of course the moats from which the underground creatures lead to the outside world. But it is also a creature from the outside world, a level to the underground world. These levels have guarded the underground world for hundreds of millions of years, allowing the ancient creatures that have survived hundreds of millions of years in it to recuperate.

So that in this underground space, there are not even rats and snakes. Therefore, the most authentic primitiveness has been preserved. Yun Lei and Rao Ya were not only unwilling to destroy these, but also deliberately laid formations and traps at some exits. Even if it is a creature from the outside world who coincidentally enters this underground world alive, there is only one way to die in the face of these formations and traps.

Finally, in the underworld, a crack was found in the dome of dark rock, which could accommodate one person to enter and exit. Through this deep rift, Yun Lei and Rao Ya slowly crawled back to the surface. And when they appeared on the surface, they found themselves on the top of a mountain peak on the Tibetan Plateau, and below the mountain was a wasteland that looked completely lifeless!