After seeing Zhou Nan's ruthlessness, middle-aged people don't dare to lie at all. Just lowered his head, sorted out his thoughts, and quickly stated.

"Senior, this law enforcement prison is a place built by the Xuanhuo Sect a long time ago to hold criminals. There are two floors in total. The first layer is where the disciples of the Enlightenment Period are imprisoned, and the second layer is where the predecessors of the Foundation Building Period are imprisoned. ”

"The space on these two floors is extremely large and covers an extremely wide area, and it has not been explored clearly. In this law enforcement prison, there is not the slightest aura. Use a little less mana. Those of us who have run out of mana and have no spirit stones or pills to replenish have no choice but to retreat here and can only wait for death. ”

"But for some reason, some terrifying zombies appear in this law enforcement prison from time to time. In this dark environment, these guys are very elusive and powerful. Some terrifying zombies, even the predecessors of the foundation building period, can't be provoked. But the Xuanhuo Sect ordered us to encircle and suppress these zombies from time to time, and obtain the corpse crystals in the zombies' bodies in order to exchange for some necessary things. As a result, most of the people who entered the law enforcement prison lost their lives as a result. The younger generation is blind and has no choice but to act like the seniors. I hope that the seniors will not remember the villain, and leave the villain a dog's life!"

···

After half a cup of tea, the middle-aged man finished telling everything about himself tremblingly. begged again and again to degrade himself to nothingness, but he was still ruthlessly killed by Zhou Nan. Without the slightest guilt, holding his chin with one hand, Zhou Nan pondered quietly.

"I can't imagine that there are such strange things in this law enforcement prison. Hunting zombies and getting corpse crystals? It's really bloody! No matter, find a safe place first, get the Hantan Ice Lotus, and then advance to the foundation building period. ”

Zhou Nan thought about it for a while, so he didn't stay any longer, hurriedly shot out a dozen fireballs, and after destroying all the corpses on the ground, he casually found a passage and got in.

The law enforcement prison is deep underground, the earth qi is concentrated, and the yin qi is extremely heavy, if there are a large number of corpses, it is not surprising that corpses will be transformed and zombies will be generated. I just don't know how the Xuanhuo Sect found such a place, and what do you want that corpse crystal for?

Corpse crystals, as the name suggests, are the corpse qi crystals in the body of zombies. Just like the demon beast Neidan, it is the most important thing for each. But the corpse crystal is different from the demon beast Neidan, as long as the zombie's corpse qi is heavy enough, it can be formed, and there is no level limit. However, the demon beast inner dan is different, only the demon beasts of the third order and above have a certain chance of forming the inner dan.

The environment on the first floor of the law enforcement prison is very similar to that of a flint mine. With the previous experience, it didn't take long for Zhou Nan to find a safer passage.

Slowly glanced around, and seeing that no one else was paying attention, Zhou Nan took out a flying sword, like cutting tofu, chopping stones, and quickly opened up a secret room. After arranging the formation, he nodded with satisfaction and got busy.

Stuffing a skull-sized night pearl into a groove and arranging the secret room at random, Zhou Nan stood in the center of the secret room and took out the sealed dragon coffin from the storage bag.

With his left hand, he pinched a magic trick and opened the sealed dragon coffin. Staring at the Hantan Ice Lotus, which was intact and still sealed, Zhou Nan breathed a sigh of relief, lowered his head, lay on the edge of the sealed dragon coffin, and carefully studied it.

With the protection of the sealed dragon coffin, until now, this Hantan Ice Lotus is still the same as before. A few large, warm pale blue leaves, a thumb-sized trunk, topped by a nine-petaled crystal lotus plate. It's like a flower that is so beautiful that it only exists in fantasy. It can be viewed from a distance and cannot be blasphemed, and the wonderful ones are a little abnormal.

I don't know if it's because of the secretion of pure spirit saliva or not, this Hantan Ice Lotus doesn't have the slightest aura of elixir. It's like a piece of ice, always cold. Zhou Nan searched for a long time, but he didn't find anything useful.

"Could it be that this Hantan Ice Lotus is a waste product?" Zhou Nan lowered his head and pondered.

"Impossible, impossible, how can something that can contain such a treasure as pure spirit saliva be a waste product?" With a turn of his head, Zhou Nan immediately denied his thoughts and studied it again.

In this way, half a month of time passed quickly in Zhou Nan's research and exploration, which was sleepless and forgetting to sleep and eat.

Today, the emperor has lived up to his painstaking efforts, and Zhou Nan's research has finally achieved some results. In recent days, after repeated research and experiments, Zhou Nan finally found a clue.

Hantan Ice Lotus, just like her name, is noble and elegant, and her whole body exudes an elegant and dusty breath. Do not tolerate external objects, and cleanse yourself. Therefore, as long as the Hantan Ice Lotus comes into contact with the slightest breath from the outside world, it will quickly wither, turn into ashes, and disperse with the wind.

If it weren't for the sealed dragon coffin, which could isolate the outside breath and form a closed space inside, Zhou Nan would not have a problem with this delicate cold pool ice lotus. At this moment, he was sealing himself and Hantan Ice Lotus in the sealed dragon coffin, cutting off all contact with the outside world.

Now, he was stretching out his left hand, running the "Soul Refinement" to slowly inject his mana into the Cold Pool Ice Lotus. The cyan mana flowed through Zhou Nan's meridians and fingers, like a stone sinking into the sea, into the ice lotus, and disappeared.

But Zhou Nan was not in a hurry, he just maintained his current state, absorbing spirit stones to restore mana, and at the same time concentrating on outputting mana. Time flies quickly in Zhou Nan's cookie-cutter and cautious meditation.

That's it, just in a flash, three months passed.

opened his eyes and looked at the crystal lotus plate blooming in Hantan Ice Lotus, Zhou Nan's face suddenly flashed with a thick joy.

"Sure enough, this Hantan Ice Lotus itself has no medicinal value. It's just a tool to absorb spiritual power and purify it into pure spiritual milk and spiritual liquid. To put it bluntly, it is a medium, but it is an extremely precious medium. A small drop of crystal liquid with a rich fragrance in the face plate was filled with a small bottle, and Zhou Nan said in a low voice.

It turned out that after studying the Hantan Ice Lotus, Zhou Nan inadvertently discovered that if he injected mana into the Ice Lotus, the Ice Lotus would purify the mana through its own special ability to form a more refined spiritual power.

After discovering the special effect of the Hantan Ice Lotus, Zhou Nan was overjoyed. didn't care about anything else, and hurriedly entered the mana purification stage. This experiment lasted for three months. Sure enough, Zhou Nan's conjecture was perfectly confirmed.

In the past three months, Zhou Nan consumed as many as five or six hundred spirit stones. But he didn't feel a little distressed. Because, the effect of Hantan Ice Lotus is really against the sky. As long as he can make good use of this role, Zhou Nan can't imagine how wonderful his future will be.

In the following days, Zhou Nan did not hesitate at all, and plunged headlong into the retreat of refining spiritual liquid and purifying mana. This retreat is five years long.

In the first three years, Zhou Nan used up the tens of thousands of spirit stones on his body. However, the purified spiritual liquid still could not meet his needs in the advanced foundation building period. didn't dwell on this issue too much, because there was no aura in this law enforcement prison, so Zhou Nan hit the idea on those prisoners.

Sure enough, after making a few shots and robbing a large number of prisoners in the Enlightenment Period, Zhou Nan gathered thousands of spirit stones and persisted intermittently for another two years.

During this period, because of the robbery, Zhou Nan was also chased and killed by some powerful forces in the prison, but he avoided them. When he went out, Zhou Nan also encountered a lot of zombies.

With interest, Zhou Nan also shot and killed a few. These zombies with corpse crystals in their bodies are at least more than thirty percent more powerful than zombies in the outside world at the same level.

However, Zhou Nan's strength has already surpassed the limit of the Enlightenment Period and entered the level of the Foundation Building Period. Therefore, in the case of picking white-haired zombies for research, Zhou Nan was not hindered in the slightest, and figured out the strength level of the zombies in this law enforcement prison.

Of course, these are all off-topic. After five years of retreat, Zhou Nan finally walked out of the sealed dragon coffin. After stretching his waist and moving his muscles and bones, he smiled deeply when he looked at a big jade bottle in his hand.

"After five years, I have finally refined enough spiritual liquid, as long as I take it with Zhuji Dan and advance to build the foundation, it will be just around the corner!" staring at the jade bottle in his hand, Zhou Nan only felt a good mood for a while, and it was indescribably comfortable.

In the following month, Zhou Nan packed his things, left the secret room, and began to move on the first floor of the law enforcement prison. Although there is no scenery in this stone and dark underground, and it is even a little boring, Zhou Nan also watched it with relish.

A month passed, after wandering around the first floor of the law enforcement prison, Zhou Nan released the pressure and boredom of the five years of retreat, and returned to the secret room with a relaxed face, arranged the formation, and entered the retreat again.

Only this time, what he has to do is no longer to propose mana and refine spiritual liquid. Instead, he had to get out of the second step of his path of cultivating immortals, that is, building a foundation.

After resting for three days and taking a bath in incense, Zhou Nan entered the coffin of the sealed dragon and sat in front of the Hantan Ice Lotus.