"Yes, this formation will be of great use after it is built. In the future, if we encounter someone who is unfavorable to our Wuji Palace, we can raise the cultivation of a large number of disciples to a level in a very short period of time.

So this formation must either not be built, if it is built, it must be built!" Cheng Yu said seriously.

Wuji Palace is not like the Cheng family, the Cheng family is still too weak and has no social status. But Wuji Palace's fame is so big, and its strength is so strong, who dares to provoke Wuji Palace easily?

It is not uncommon to have spiritual veins in such a sect, not only Wuji Palace, but even Xuantian Sect, Heavenly Demon Sect, Fahong Temple, etc., they all have spiritual veins in their sects, which is not a secret.

But even if they knew, what would they dare to rob? They really didn't want to live.

But in the Cheng family, he didn't dare to take out the spirit veins to strengthen the formation, that would only attract more enemies. Therefore, he only used a small piece of spirit crystal, so that even if someone coveted it, at most he would lose a spirit crystal.

"There is some truth in what you said, then it's up to you!" Qing Yuanzi thought for a while and said.

"As for alchemy, although you don't need it now, but other fellow disciples also need it, if you have Tiantong Grass, I can refine some Mahayana pills for the sect!" Cheng Yu said.

"Mahayana Pill, can you refine Mahayana Pill?" Qing Yuanzi and Qing Xuzi said in surprise.

The Mahayana Pill is the pill needed to break through the advanced Mahayana Pill in the Merge Period, and even they don't have such an elixir in the Wuji Palace. No matter what quality Mahayana pill is, it is extremely precious.

There was once a low-grade Mahayana Pill in the Qiongyulou auction house, and I heard that it was robbed crazy, and finally bought it at a very terrifying price.

If Cheng Yu was able to refine the Mahayana Pill, wouldn't the Wuji Palace be able to greatly increase the success rate of the disciples in the advanced Mahayana stage.

"As long as there are herbs, I can indeed try to refine them, but I can't guarantee success, nor can I guarantee the quality, it is very likely that it is just a low-grade Mahayana pill. Cheng Yu said with some expectation.

Because the grade of the Mahayana Pill is too high, his Feng Yan is already a little insufficient, unless Feng Yan can advance to become Long Yan, in that case, he will be able to refine the best Mahayana Dan.

But the opportunity is rare, there are so many medicinal materials in Wuji Palace, he can completely try to refine them!

"Okay! Tiantong Grass is available in our sect, because our Dan Master has no way to refine Mahayana Pill, so Tiantong Grass has always been stored. Qing Yuanzi said happily.

"Actually, although you don't need to cross the tribulation now, I can also help you refine some tribulation pills first, even if the master and uncle can't use it, they can also be used by other people in the sect!" Cheng Yu thought for a while and said.

"What????, can you still refine the Crossing Pill?" the two said in shock.

If Cheng Yu was able to refine the Mahayana Pill really surprised them, but refining the Tribulation Pill was really shocking. Because, they had never heard of someone successfully refining the Tribulation Pill, this was just a pill that appeared in the classics, and no one could really refine it.

"I dare to lie to you, I only exposed this secret for the sake of the future of your Wuji Palace, but as I said just now, I can't guarantee success, nor can I guarantee quality!" Cheng Yu said with some smugness.

Although his strength is not as good as these two old guys, his ability in other aspects may not be comparable to them.

It's a pity that all he has now is Feng Yan, if it is Long Yan, as long as it is not an elixir, he is not restricted by cultivation and realm at all. As long as there are enough materials, he can refine all the nether elixirs.

"You kid can't believe all of his words, so let's do it, you first refine a Mahayana Pill and come out and take a look. If we can, we will let you refine the Tribulation Pill again, otherwise, we can only wait a little longer, and wait for your alchemy strength to go further, and then refine it for you!" Qing Yuanzi thought for a while and said.

The medicinal materials used to refine these pills were all extremely precious, how could he try to play.

"That's okay!" Cheng Yu thought about it and felt that it made sense.

After all, he was not sure that he could refine the best elixir, and for him, if he couldn't refine the best elixir, it would not be of much significance.

After all, the best elixir can increase the success rate by 100%, while the top grade can increase by 80%, the middle grade is 60%, and the lower grade can only increase the success rate by 40%.

If you can only refine the lower grade pills, it will be too wasteful of resources, it is better to turn your own Feng Yan into Long Yan in the future, and all the pills in the human world can be refined.

---------------------

The next day, Qing Yuanzi took Cheng Yu to the back mountain!

Disciples are usually not allowed to enter this back mountain, and only disciples who have been granted permission can enter.

"Is there anything secret here?" Cheng Yu asked curiously, and after walking into the back mountain, he obviously felt that the aura here had become very rich.

"Because the spiritual veins of our sect are here!"

"Is there only a spiritual vein, and there is no need to be so secretive!" Cheng Yu said.

"You'll find out for yourself in a moment!" Qing Yuanzi shook his head and said.

"This ......" The two of them walked inside, and it turned out to be a clearing lot, and a huge stone in the clearing was floating in the air, and there were six crystals floating around this crystal, and under this big stone was a large array of yin and yang.

"Uncle Shi, the six pieces around that are spirit crystals!" Cheng Yu asked curiously.

"That's right! those six pieces are indeed spirit crystals!" Qing Yuanzi nodded.

"But what is this boulder in the middle? Why is it so dark? Is there any mystery in this?" Cheng Yu didn't understand what this thing was, this stone was pitch black and hung in the air.

"This is what our sect has passed down from generation to generation!"

"It's been handed down from our sect, but it's just a stone, at most a strange dark stone. Cheng Yu said puzzled.

There is nothing special about this stone except that it is pitch black, is there any mystery in the ancestor of Wuji Palace, such a big stone has come down?

"This is the secret of our sect, we can't confide it casually!" Qing Yuanzi shook his head and said.

"Uncle Shi, no, just our relationship, you tell me!" The more Qing Yuanzi was reluctant to say, the more curious he became.

Others didn't dare to talk nonsense when they saw Qing Yuanzi, and only Cheng Yu dared to talk to Qing Yuanzi like this.

"It is said that this is a secret of the sect, only the head of the sect can know, even if it is your master, he doesn't know about it!" Qing Yuanzi shook his head again, unwilling to say more.

"Isn't it, I don't even know the identity of my master?" Cheng Yu heard this, but he was even more curious!