The frequency of the electromagnetic waves he uses is not too high, about tens of megahertz, which is comparable to the harmonic frequency used by ordinary FM radios. Electromagnetic waves of this frequency belong to the range of short waves in the classification of electromagnetic waves in the secular world, and they are the frequency bands used in general communications.

Since he couldn't form a continuous resonance, he probably didn't really find the natural frequency of this formation.

He knows that the natural frequency is fixed, and the best way to form a resonance with it is to input an electromagnetic wave with exactly the same frequency, if the frequency is not exactly the same, then it should be possible to input an integer multiple of the high-frequency electromagnetic wave, but it will lose a certain amount of energy.

If the input frequency is lower than the natural frequency of the formation, it will be difficult to form a resonance, and the total amount of input energy is too small to be consumed by the formation after multiple oscillations, and if it cannot form a continuous energy accumulation, it will not be able to have a significant impact on the formation.

There is a worse situation, that is, there is no integer multiple relationship between the input frequency and the natural frequency of the formation, but there is a common multiple between the two, for example, the natural frequency is 5, and the input frequency is 6, then every 6 oscillations of the formation, there will be a resonance with the input stimulus frequency, so that if you want to destroy the formation, you must input at least nearly ten times more energy. Again, this is not much the difference between the two. If the two frequencies are quite different, say 100 and 101, then the problem is even more serious.

In this regard, he did not have a good way, so he could only slowly input the electromagnetic wave frequency at high speed, and try it little by little, just like tuning the radio in the seventies and eighties. This is much more complicated than tuning a radio, after all, the frequency range of tuning a radio is limited, and he has to start with a long wave of low frequencies, and gradually transition to medium waves, short waves, and microwaves of high frequencies, and finally it may reach the level of centimeters, millimeters, and even micrometers. Of course, his strength is limited and he can't generate ultra-high frequency electromagnetic waves with too short wavelengths, but he believes that the natural resonance frequency of this formation will not be too high to be too perverted.

After resting like this for a while, Tian Xu began to try to input electromagnetic waves of different frequencies from low to high, and the point where resonance can occur on the formation soon reappeared, and at the beginning it was still the same as before, appearing once in ten seconds to tens of seconds, with the increase of frequency, the appearance of such resonance points gradually accelerated, and when the frequency was about to reach the limit frequency that he could emit, the resonance appeared again.

This time it was different from the past, after the resonance appeared, it did not disappear again, but was firmly captured by him. He maintained this fixed frequency and increased the amplitude of the output electromagnetic waves, and when the power increased, the entire palace vibrate.

Just a second or two after the resonance appeared, the resonance point that did not disappear gradually expanded, and a hole appeared where the resonance point appeared, and gradually expanded, and after a few seconds, the hole had expanded to the size of the mouth of the bowl.

At this moment, the palace in which he had been trapped suddenly disappeared, and in the blink of an eye, he was already outside the palace, and when he looked at the palace again, it had already returned to its original appearance. The realm he had been carved out of at the beginning was outside the room, controlled by the Dan Ling, who had also remained outside. Seeing Tian Xu come out, Dan Ling suddenly entered his spiritual realm with that realm, and became one with his remaining realm again.

Tian Xu's ability to control electromagnetic waves is far less strong than that of other five-sense signals, just a few tens of seconds, he is already extremely tired, not only the fatigue caused by the loss of spiritual energy, but also the mental fatigue, which envelops him tightly, making him just want to close his eyes and sleep first.

Fortunately, after Dan Ling entered his spiritual realm, it injected new vitality into him. Dan Ling shared the spiritual realm and thoughts with him, and the Dan Ling who stayed outside the room was full of energy, and after merging with him, he made up for part of the loss of his energy, so that he could continue to cheer up and face the crisis behind.

At this time, the middle-aged man in white appeared on the top of the room again, injecting a divine sense into Tian Xu's thoughts. That divine consciousness contained a large amount of information, and the origin of this Sea King's Palace was sent to his mind at once.

From this information, Tian Xu learned that this Sea King Palace was originally the beast king of all the spirit beasts in the Pacific Ocean - the shell of the mirage, which was originally a big mussel, and was designed by the Chiyou who fled into the sea during the battle between the Yellow Emperor and Chiyou. When the mirage was killed, it was already a ninth-level spirit beast, which was equivalent to the cultivation realm of the peak of the human cultivator's earth, that is, the strength of the Flying Ascension Realm, which was far from being comparable to the current cultivators. And the middle-aged man in white is a divine consciousness left behind after the mirage.

This mirage was originally close to complete soul cultivation, its shell was an artifact-level magic weapon, and because the powerful mirage was with this shell for life, after the mirage, a large number of spiritual formations were also left in this shell, and after a long period of ownerlessness, it evolved into the current Sea King Palace.

Every fifty years, the shell will breathe like a mirage, and when it breathes, the shell will expel some debris from the body, and then absorb the aura and spiritual substances from the outside world into the body. Cultivators, spirit beasts, and demonic beasts from the outside world can take the opportunity to enter the shell when they breathe out of the shell, and challenge various formations here, breathing the high concentration of pure aura inside the shell, and the cultivation realm will be significantly improved.

In addition, there are some physical magic weapons in the shell, most of these items are left by the cultivators who died in them when they came here to experience the past, after the special environment in the shell, these magic weapons will also be upgraded, and some even reach the level close to the artifact, which is tantamount to a treasure for the cultivation world outside that lacks spiritual energy.

After the shell breath is over, if you stick to it inside, the cultivators who don't die will be thrown outside, and the treasures that the cultivators have obtained inside will be thrown out together. It was precisely because of this that although more than half of the cultivators who entered the Sea King's Palace for training would die in it, every time the Sea King's Palace was opened, the cultivators who learned the news were still scrambling to find ways to enter the experience.

This Sea King Palace itself is a relatively powerful artifact, and it is also strongly wary of cultivators who enter it, and cultivators whose realm has reached the middle stage of the earth level will be turned away by it. In other words, the only people who can enter here are Saint Realm cultivators, sixth-level spirit beasts and demonic beasts, as well as low-grade immortal weapons, if they are higher than these, they will be blocked out of the door of the Sea King's Palace.

The Medicine King Dou and Yin Yang Ding that Tian Xu carried on his body were both artifacts, and the realm of the Medicine King Dou had reached the middle grade artifact, and his own strength was about the same as that of the Sea King Palace, and the Sea King Palace was powerless to prevent her from entering, and could only block her external senses while she was in a dormant state, so that she could not play a role.

As for the Yin Yang Ding, it was just a low-grade artifact, and the loss of vitality was so great that it could not reach the strength that an artifact should have, and it was also easily suppressed by this Sea King Palace. The Shennong hoe and the hundred grass whip in the Medicine King Bucket, as well as the Yiguang Sword, which is also a low-grade artifact, are protected in the body by the Medicine King Bucket, and this Sea King Palace cannot know about their existence.

Finally, the white-clothed middle-aged man, that is, the Mirage King's divine sense, said: "Young man, your performance is quite good, you are the first person I have met in so many years who intends to break the formation by destroying my formation, and may succeed, with you as the king of the earth, you should be able to deal with the enemies of the fairy world." I promised you at the beginning that I could answer your three questions, and now you can ask. Remember, you have to think about it before you ask, and you can only ask three questions, whether I can answer it or not. ”

Tian Xu said without thinking: "Okay, I remembered." The first question I have to ask is, the girl who came in a little earlier than me is—" He said as he condensed the appearance of purple smoke around him with his aura and showed it to the Mirage, "How can I find her?"

The Mirage King glanced at Ziyan's appearance and said, "This girl is in one of the three palaces in front of you on the left, and if you look in this direction, you should be able to find her." This girl's potential is good, and there should be no danger in the short term. ”

Tian Xu then asked, "The second question, how can we ensure the safety of Ziyan?"

The Mirage King looked at Tian Xu intently for a while, and said: "It seems that you have a lot of importance for this girl, then I will tell you the truth, you and I have no way to guarantee her safety, since she has come to this Sea King's Palace, she can only rely on her own efforts to defeat the attacks of the various experience formations and other cultivators here, in order to survive safely, there is no other way." In addition, I have a piece of advice for you, in this Sea King's Palace, there is a strong psychedelic formation, even if you are familiar with each other, you may not be able to recognize each other when you meet on the other side. It's even difficult to tell whether the other party is a local cultivator or a demon cultivator, whether it's a demonic beast or a spirit beast, even if you and that girl meet, you may not be able to recognize each other, so be careful and careful. ”

Tian Xu was a little dissatisfied with the mirage's statement, and said, "As a powerhouse on the earth, how can you let the demonic beasts and demonic cultivators who enter here ignore them, and treat them equally?"

The Mirage King said: "You are mistaken, I am no longer the king of the sea spirit beasts, I am just a shell left behind by the mirage king after his death, an artifact, as an artifact, what ability do I have to treat other cultivators? Okay, I've already answered the three questions, I lost a lot when I met you, so I have to take a good rest, wait for the next unlucky guy to come in, so I can earn some vitality, so I won't accompany you. After saying that, he hid his figure and never spoke again.