Lei Yindan Zhang Yu had never refined, but he was extremely clear about the steps of refining.

As soon as his mind moved, the fire transformation technique was activated, and a wisp of flame rose from his fingertips, and then ignited the alchemy furnace.

Looking at the raging flames, Zhang Yu's pupils also shrank slightly.

The first step in refining the elixir is naturally to refine the essence of various elixirs, and the step of refining the elixir of the Lei Yin Pill is not cumbersome, the key is to be proficient in mastering the changes in fire temperature.

Every step must be precise to the extreme, otherwise the slightest negligence can lead to all efforts being wasted.

The temperature was enough, and with a move from Zhang Yu's hand, a piece of burning thunder wood fell into the Dan furnace.

The Burning Thunder Wood is a rare dual-attribute spiritual material of thunder and fire, and the quenching process needs to be attacked with rapid fire, so that the layer of thunder pattern on its skin can be refined and dissolved.

Keeping these precautions in mind, Zhang Yu's palm moved, and the flames soared, completely engulfing the entire Dan furnace in an instant.

There was a crackling sound in the Dan furnace, and from time to time there were thunder arcs, as if they were deliberately disturbing Zhang Yu's state of mind.

However, Zhang Yu's heart was like water, covering the entire Dan furnace with the power of his soul, and every slight change could not escape his observation.

Looking at the scorching thunder wood essence flowing in the Dan furnace like magma, Zhang Yu raised his hand, the furnace lid flew up, and a navy blue flower flew into it, and the terrifying temperature instantly ignited it.

Between breaths, the impurities completely dissolved into nothingness, and only a pile of blue-gray particles remained in the scorching thunder wood.

Next is the Tianmu cicada, the heavenly herb, the snake bone flower......

Each elixir has a fixed order in which it is added, and once this order is disrupted, it may cause the medicinal properties to clash and directly lead to the failure of refining.

"It's time to add the Thunder Clam Demon Crystal, be careful with this thing. Zhang Yu muttered to himself in his heart, and carefully threw the Thunder Clam Demon Crystal into the Dan furnace.

"Peng!"

Before Zhang Yu could react, the entire Dan furnace was rioting, and the elixir essence that he had finally refined with great difficulty instantly turned into black slag.

"Damn, what's going on?" Zhang Yu was also a little confused, obviously all the steps were not wrong, but why did he still fail to refine.

"There is demonic energy contaminated on the thunder clam demon crystal, and if you don't even get rid of the demonic energy, you want to add it to the Dan furnace, it's already good if you don't have a fryer. Old man Gan said coldly.

He had been standing on the side and observing, and as a Seven-Rank Dan Dao Sect Master, he naturally discovered Zhang Yu's mistake at a glance.

A word woke up the person in the dream, Zhang Yu patted his head, and he suddenly realized.

In most cases, the demon crystal can be directly smelted as an elixir, but sometimes, some elixirs are extremely sensitive to the demon qi in the demon crystal, as long as it appears a little, the nature will change greatly, and the heavenly herb is one of them.

Prior to this, Zhang Yu had added Heavenly Herbs to the Dan Furnace, and the Heavenly Herbs would immediately transform into Demon Xuanjing when they encountered demon qi under high temperatures, and Demon Xuanjing and Burning Thunder Wood were mortal enemies who never got along, and once they met, they would explode like explosives.

"Thank you Gan Lao for mentioning it. Zhang Yu said gratefully.

If Old Man Gan didn't say it, he would probably have to waste a lot of time to figure out the truth.

"Don't thank me, I just don't want you to be blown up, otherwise if it gets out, I should say that you were killed. Old man Gan replied coldly

Zhang Yu smiled bitterly, and did not continue to entangle, and began to prepare for the second refining of Lei Yin Dan.

And with the first lesson, this time Zhang Yu's movements became more and more skillful, and every step of the elixir refining was extremely perfect.

Once again, it was his turn to purify the Thunder Clam Demon Crystal, and Zhang Yu wiped it out with a casual touch, and sure enough, there was no abnormality in the Dan Furnace.

"It's finally time to get to Ning Dan. Looking at the various purified elixir essences in the Dan furnace, Zhang Yu's mood also became more solemn.

Ning Dan is the most test of patience and control of soul power, the whole process must be done in one go, and a slight mistake can be a failure.

However, although Zhang Yu was only a fourth-grade junior alchemist, his soul power was comparable to or even surpassed that of a fifth-grade alchemist, so he was absolutely confident that he could complete this last step.

The essence of the same elixir began to merge with each other, and at this moment, the elixir with completely different properties perfectly fused into one, which was the mastery of the alchemist.

They can find out the characteristics of each elixir, and complement each other through another elixir, so as to stimulate the deepest effect of the elixir and make the most of them.

The flames slowly weakened, a trace of white gas came out, and several pills in the Dan furnace gradually took shape, and Zhang Yu could even smell the refreshing fragrance.

However, Zhang Yu did not relax, because there was still the most difficult level left - Hedan.

Lei Yin Dan is not an ordinary four or five low-grade pills, its medicinal effect is extremely violent, just like a wild horse is difficult to tame, so in the end, it must be carried out, and only one can be refined at a time.

It is precisely because of this that the number of Lei Yin Pills in the world is scarce, and it has always been in short supply, and the price even exceeds the vast majority of five-grade pills, which is enough to be comparable to ordinary six-grade pills, and among the low-grade pills, it is enough to be regarded as an outlier.

This was the first time to Hedan, so Zhang Yu couldn't help but feel a little nervous in his heart, and the majestic soul power roared out, completely controlling the prototype of several Thunder Yin Dan in the Dan furnace.

"He!" Zhang Yu snorted, under the traction of soul power, the prototype of the Lei Yin Dan collided violently, and the powerful power spread, and the inside of the Dan furnace that hit rang loudly, if it weren't for the good quality of the Dan furnace provided by Old Man Gan, I am afraid it would have exploded.

"Three turns of the flames, nine curves of the intestines!" The prototype of the five pills was about to fuse the only one, and the cold voice of Old Man Gan suddenly came from Zhang Yu's ears again.

Zhang Yu was stunned for a moment, but he came back to his senses in an instant, and was about to change the power of the flame, but it was too late, and the pill was instantly condensed and formed, but unlike the normal pill, this Lei Yin Pill was oval-shaped, and the surface was pitted, although it was barely regarded as a Cheng Dan, but the actual effect of the medicine had been greatly reduced, and the buyer would not look at it at all.

Looking at the deformed elixir that was finally refined, Zhang Yu couldn't help but feel a little embarrassed.

The so-called "three turns of the flame, nine curves of the ileum" is a kind of flame transformation situation when refining the elixir, which means that at the last moment, within one breath, the intensity of the flame should be increased and decreased three times at a time, and so on for nine rounds.

Under the scorching flames of flickering strength and weakness, the violent temperament of Lei Yin Dan can be completely released.

One step was a mistake, and as a result, the Lei Yin Dan refined by Zhang Yu was simply a waste product.

After taking a deep breath and adjusting his state, Zhang Yu finally began refining for the third time, which was already the last chance stipulated by Old Man Gan.

The first two failures did not have any adverse effect on Zhang Yu, but instead allowed him to discover all the loopholes in his refining.

After absorbing these lessons and lessons, Zhang Yu's actions were as smooth as flowing water, and all kinds of elixirs were thrown into the Dan furnace by him without interruption, and the essence of the elixir was extracted instantly, reflecting a faint luster in the Dan furnace.

Looking at the many elixir essences that had been removed from impurities, Zhang Yu also nodded secretly.

The preliminary steps were successfully completed, and the key step of reaching Hedan was finally reached again.

Zhang Yu made a mistake here last time, and this time he will definitely not let the scene reappear.

"Boom!"

The flames in the Dan furnace instantly soared to a terrifying temperature, and even the air was about to be ignited, and there was an uncomfortable feeling of heat.

However, before anyone could get used to it, the temperature dropped rapidly, and the slightly beating flames could not help but blow the wind, as if they could be blown out in one breath.

However, this process was also extremely short-lived, and after a while, the temperature of the flame skyrocketed again.

It can be seen that when the flame is transformed like this, the elixir first absorbs a large amount of flame power, and then repels a large amount of xenomorph energy from its interior, and so on three times, the original pitted pill prototype was suddenly repaired round and smooth, and the faint blue luster shimmered slightly, like a jewel.

After warming the pill with flames for nearly ten minutes again, Zhang Yu patted the pill furnace, the lid of the furnace was lifted, and a pill the size of a dragon's eye flew into his palm, and faintly, there seemed to be a roar of thunder in his ears.

"The pill has been successfully refined, and I invite Senior Gan to taste it. Zhang Yu played a few simple pill seals to ban the pill to prevent the effect from passing, and then presented it to Old Man Gan.

Old man Gan took the elixir, turned it over and over and looked at it several times, then put it to his ear to listen, and then put it on the tip of his nose to smell, and his face became excited.

"There is the roar of thunder in the sky, the roundness of purple jade pearls, and the most commendable thing is that it is still the Bacheng Dan with eight Dan patterns, good, good, good!" Old man Gan was full of praise for the Lei Yin Dan refined by Zhang Yu, and said three good words in a row, which was enough to see the excitement in his heart at the moment.

Zhang Yu smiled slightly, he didn't have any arrogance because of this, even if he could refine the Lei Yin Pill, he was still only a fourth-grade Dan master. Compared to the Seventh Rank Dan Dao Grandmaster, there is still a long way to go.

"Boy, who is your master, who can hand over an apprentice like you, if I have the chance, I must go and meet him. Old man Gan smiled.

"Shizun is just a nameless idler living in seclusion in the mountains and forests, and I'm afraid that Gan's predecessors won't know about it. Zhang Yu said nonsense.

Now Mochen is just a soul body, and it is not suitable to come out to meet people at all, so Zhang Yu simply cut off Old Man Gan's thoughts.

"Haha, the old man also just wants to live in seclusion here, but there are always people who want to disturb my purity. The elixir will be returned to you, this is what you refined, and it will belong to you. Old man Gan smiled and threw the elixir that was still flashing with thunder to Zhang Yu.