This stone door is more than two zhang high, and the door is carved with dense various characters, but they seem to be ancient characters that are very old, and Gao Yun doesn't know any of them.

He couldn't help but think, how hard does it take to push open such a tall door?

What's even more strange is that Gao Yun found that there seemed to be only this stone gate in this small courtyard, and there was no tall building.

Originally, according to his expectations, the Treasure Hall should be a majestic palace, or a tower reaching into the sky, but what came into view was nothing.

Just as he was muttering in his heart, Ying Wutian had already walked to the stone gate, and a palm lightly slapped on the stone door,

Immediately, Gao Yun didn't even feel any breath coming from the elder's hand, and the heavy sound of "crunch" immediately oscillated in all directions.

The incomparably heavy stone door slowly opened in his stunned gaze!

As the stone door opened, a long-sealed quaint atmosphere immediately hit the face.

Gao Yun's heart immediately sank, it seems that this treasure hall was last opened at least one or two decades ago.

"Alright, you go in. Ying Wutian withdrew his palm and said to Gao Yun.

His meaning was obvious, it was a place that only the lord of the city could set foot in, and no one else could.

Nodding slightly, Gao Yun took a deep breath and walked into the stone gate.

For a moment, Gao Yun felt that he was surrounded by a bright light.

Suddenly, I felt the soles of my feet lighten, and my body spun with it.

"This feeling is so familiar......," Gao Yun immediately understood, "It turns out that this treasure hall is located in another dimension, and that stone door just opens the portal." ”

Just when Gao Yun was slightly distracted, his body suddenly stopped, and his feet suddenly stepped on the ground.

"It's here. ”

As the strong light disappeared, what appeared in front of Gao Yun's eyes was a huge cave!

Looking at the cave that was so high that he couldn't see the top, Gao Yun couldn't help but secretly marvel.

The soul tricks that the disciples of the Imperial City Academy learned were all selected in the soul trick building in the academy, where the soul tricks were neatly placed on the shelves in rows, and the scrolls of this treasure hall were placed in the holes in the stone wall of the cave.

Looking around, he immediately realized that there was no entrance or exit to this cave, which meant that he was directly teleported into the cave.

Gao Yun couldn't help but be stunned.

I've chosen something, what should I do when I want to go out?

Although he knew that the Chief Elder would definitely not harm him, Gao Yun still felt a little uneasy in the face of this mysterious cave.

However, he immediately discovered another thing, the soul power here was very strong, and it was very suitable for cultivation.

He suddenly remembered that when Ying Wutian introduced the Treasure Hall to him before, what he said seemed to be: all the city lords of all dynasties must enter the Treasure Hall and cultivate high-level soul techniques suitable for themselves.

Practice!

Gao Yun immediately felt that he had captured a key.

It seems that the soul recipe here cannot be taken away, only cultivated.

"Forget it, let's choose a soul trick first and then talk about cultivating it. ”

As for the question of how to leave this kind of unanswerable question, Gao Yun immediately skipped it.

With a tap of his right foot, his body immediately floated into the air, looking at the hundreds of neatly arranged holes around him.

On the outside of each hole, there are faint gray light curtains, through which you can vaguely see the soul tricks or treasures inside.

However, as far as he could observe, the soul trick was the majority, and only the top two circles of holes contained various weapons and equipment, or some strange things that he couldn't even recognize.

There were also a few holes, and the light curtain was gone, and it was empty, indicating that something had been taken.

At this time, at the gate of the small courtyard, Zhu Ling couldn't help but be stunned when he saw Ying Wutian walking out slowly.

"Elder, why didn't my father-in-law come out......"

The old man smiled: "It's not so fast, it will take three days at the earliest, and a month at the slowest before he can come out of it." ”

"So long?" Zhu Ling couldn't help but feel a little anxious, "Then he'll be fine inside, right?"

"Don't worry, if he can't hold on, he will naturally be teleported out. Let's go back and rest first, and someone will tell you when he comes out. ”

Listening to Ying Wutian's words, Zhu Ling calmed down a little, and glanced at the stone gate in the courtyard again, and then slowly turned around and left.

At this time, in the cave, Gao Yun slowly lowered his figure, scratched his head, and was just about to walk towards one of the caves.

Suddenly, a gray light cluster appeared in front of him, and immediately turned into the appearance of an old man with white eyebrows.

"Huh?" Gao Yun looked at the old man's image and said curiously, "Who are you?"

The old man twisted his beard, looked Gao Yun up and down, and then shook his head slightly, not very satisfied, and then said, "I am the guardian of this Netherworld Secret Realm. ”

"Netherworld, isn't this the treasure hall of our Imperial City? Gao Yun blinked, even more confused.

"What's there to tangle with the name. The old man rolled his eyes a little impatiently, and said coldly, "But you don't have much time left, hurry up." ”

"Hurry?" Gao Yun was confused, "Hurry up?"

"Nonsense! Go and practice the soul formula! Every full month, I will release a phantom to fight against you, you can continue to stay here if you win, and if you lose, you will get out. The old man looked at Gao Yun with a hint of banter in his eyes, obviously not optimistic about him.

"What kind of strength are the phantoms?"

"When the first month arrives, it will be released in the triple realm of the earth, the next time it will be the sixfold of the underworld, and then the ninefold of the underworld and the three types of the heavenly underworld...... And so on, but after reaching the Netherworld Emperor Realm, it will change to one heavy and one more to increase the difficulty. ”

Hearing this, Gao Yun suddenly gasped: "Doesn't that mean that in seven months, I will face the opponent of the Netherworld Emperor Realm?"

"That's true, but you'd better get past the first few levels. ”

As the old man spoke, he muttered in his heart: It's quite far to think about it, and it's still in the Netherworld Emperor Realm, with your dual strength in the Netherworld, it's good to be able to pass the first level.

Gao Yun suddenly thought of another question, and asked with his fists clenched: "Dare to ask the old man, what is the highest record of the predecessors here?"

Hearing this, the old man was almost furious.

He had never seen a person like Gao Yun, who was not in a hurry to cultivate as soon as he came in, but instead had enough to eat and ask some boring questions, if it weren't for his duty to answer questions, he would have burst into foul language at this kid who didn't know the height of the sky.

After pondering for a long time, he finally endured it and said fiercely: "The highest so far is thirteen months, passing the sixth level of the Netherworld Emperor Realm, and failing to impact the seventh level, with your current strength, it is impossible to surpass this record." ”

Gao Yun nodded, he also knew where his limit was, and he wouldn't be too ambitious.

"Old man, there is one last question," Gao Yun caught a glimpse of the old man's face sinking into the water, and said with some hesitation, "Can I ask?"

"Ask!" If Gao Yun hadn't explained in advance that it was the last question, I'm afraid he would have gone berserk.

"Which of the soul recipes here is the strongest?"

Looking at Gao Yun's serious expression, the old man suddenly collapsed.

"This kid's skin is not ordinarily thick, and he actually wants to cultivate the most difficult thing as soon as he comes up, so let you taste the taste of eating deflated. ”

The old man made up his mind, and then smiled slightly: "The strongest is called the Netherworld Demon Dragon Technique, which is divided into six parts, which are called Dragon Shape, Dragon Shadow, Dragon Soul, Dragon Scorching, Dragon Destruction, and Dragon Devouring. Where they are located is the third level of the cave from top to bottom. ”

Nether Dragon?

Gao Yun immediately thought, wasn't it the Netherworld Demon Dragon that his father had used? But I don't know, what level of that huge black dragon scale claw belonged to?

"Okay! Then I'll cultivate this Nether Demon Dragon Technique!"

Gao Yun nodded slightly as he muttered to himself.

The old man's body on the side shook slightly, and he said in a deep voice, "Are you sure you want to cultivate the Nether Demon Dragon Technique?"

Feeling that there seemed to be some special meaning in the old man's tone, Gao Yun frowned slightly and said, "Yes, is there any problem?"

"No, no," the old man waved his hand again and again, and then said, "Is it to start cultivating from the first layer?"

"First layer ......" Gao Yun pondered for a while and replied, "Okay, let's start cultivating from the first layer." ”

"Okay, then I'll help you summon the guardian spirit of the first layer of the Nether Demon Dragon Jue. ”

"Guardian ......"

Before Gao Yun could react, a black dragon dozens of feet long suddenly appeared in front of him!