This is a hand with purple light all over its body, and after it appeared without warning, it grabbed the root of the tree that Chu Nan extended from in one hand.

There was even a roar coming from the big purple hand, which clearly echoed in Chu Nan's mind.

"Get out!!"

Chu Nan's heart sank.

It was clear that the big purple hand originated from the ancient castle, and after sensing its approach, it immediately took action to stop itself.

Although this purple hand exuded powerful power fluctuations, it was still within Chu Nan's tolerance range, Chu Nan snorted coldly, and used the red yang heat energy in his body to fight against it.

Rumble!

Red Sun Heat Energy erupted through Chu Nan's roots, causing flames to ignite all over his roots, releasing terrifying heat.

You can see ......

After seeing the red yang heat energy released by Chu Nan, the purple big hand was obviously afraid, and under the diffusion of purple light, the power of the entire purple big hand also exploded.

The sound of boom suddenly continued to sound from under the ground.

The two sides collided so violently that the ground shook violently.

Under this bombardment, the purple hand was gradually defeated, and the red yang heat energy released by Chu Nan was too powerful, especially in the outbreak of hot qi under this ground, it would also be blessed by these hot qi, making it even more powerful.

In an instant, the entire purple hand was already covered with cracks, and at the same time, it let out an unwilling roar.

Rumble!

Explodes directly underground.

And with the explosion of the purple big hand, from the purple big hand, a lot of hot qi suddenly appeared, which was quickly absorbed by the roots of the tree here in Chu Nan.

This made Chu Nan's growth rate reach an extremely terrifying level in an instant.

His roots took advantage of this opportunity to spread wildly.

Phew!

Phew!

The rocky soil in front of him was constantly punctured by Chu Nan's tree roots, and all the way down, gradually, he found that the rocky soil around him seemed to have changed with the intensity of the hot air, and these rocky soils also became fiery red, and the temperature soared sharply.

Phew!

When Chu Nan's tree roots traveled some distance again, flames suddenly appeared in front of him!

This is an extremely terrifying flame, which looks like an ordinary flame on the surface, but the high temperature it emits seems to be able to burn everything!

The moment Chu Nan saw the flames, he instantly understood that the hot qi in this place was emitted from this flame.

And the hot breath emitted by the flames alone can bring such tremendous growth to oneself, if you can absorb this flame directly......

How much can you improve?

Although his heart was full of expectations, Chu Nan didn't dare to absorb it directly after he had an experience, worried that he would have the situation when he absorbed Chiyang thermal energy last time.

So he tentatively touched and felt it with a tree root, and then decided whether to absorb it or not.

However, the root of the tree had just approached the flames, and before they could touch it, they were already in the heat of the flames...... Melt!

Chu Nan's heart was shocked.

The flames were more amazing than he had ever imagined.

He couldn't even touch it!

Not to mention absorption.

And the more this is the case, the more it makes him excited.

In this regard, Chu Nan was not in a hurry, so he simply let the roots of the tree stop here, absorb the hot breath here, and grow.

At present, although he still has not reached the bottom of the ancient castle, there is still some distance from the ancient castle, but after the flames appeared, the hot qi here is also quite abundant, allowing him to absorb and grow quickly.

As he grows, his roots are rapidly rising and becoming stronger.

His idea was simple, absorb the heat to grow, and then see if the situation absorbed the flames when the roots of the tree could touch the flames.

In addition to the absorption of hot qi, in terms of spiritual energy, Chu Nan did not fall behind, and grew at the fastest speed he could achieve.

After all, he didn't know how much time was left in this trial......

Every minute and every second is important to him now, and it may allow him to catch up with the people in front of him.

That's it......

He stopped here, and after absorbing the hot qi for several days, he noticed that the flames in front of him seemed to change a little as he absorbed them, and seemed to be much smaller.

At the same time, after these days of absorption, his body size has reached more than seven meters tall!

The entire trunk is also nearly four meters thick!

It's like a big tree.

And when he deliberately concentrates all the energy of growth on the roots of the tree, the growth of the roots is the most obvious.

Now his roots are not only thick and strong, but also numerous, giving him the confidence to touch the flames.

Call!

Immediately, he controlled the roots of the tree, stretched forward, and directly touched the flames in front of him.

Snort!

The flames that could have easily melted his roots before were now extended directly into the flames by the roots.

At the same time, there seems to be a strong black cortex on the surface of these roots, so that the flames cannot destroy this cortex under the incineration, and naturally cannot pose a threat to the roots.

And after Chu Nan's tree roots extended into the flames, he suddenly felt an unusually strong hot breath from the flames.

He gradually discovered ......

Flames are not directly absorbed!

It can only absorb the heat of the flames.

In fact, the entire flame is made up of many hot gases, but within the flames, there is a core flame!

Right now, after Chu Nan came into contact with the core flame, he began to absorb it.

Compared with the general hot qi, the growth brought by the core flame is more obvious than the hot qi.

After absorbing it, Chu Nan's tree roots also changed again, and they were greatly enhanced.

And when he absorbed the core flame, the flames in front of him quickly dissipated.

At present, he is on the second stage, and he is almost at the end.

The second stage of growth is more difficult and lasts longer than the first stage.

If it weren't for these hot qi and core flames, if he just relied on the aura to absorb it, Chu Nan visually estimated that even with his absorption speed, he would have to absorb it for at least a month or more before he had a chance to reach the end of the second stage.

The absorption of the Core Flame made him feel that the improvement brought by the Core Flame was great.

He was eager to absorb more Core Flame in order to enter the third stage as soon as possible.

According to his speculation, if he could enter the third stage before the end of the trial, then among the many cultivators this time, he should be able to enter the second echelon!

So, his roots continued to spread forward, still aiming for the underground of the castle.

As he walked forward, he encountered the flames again, and the number of flames increased, and the terrifying heat emitted was also extremely terrifying.

Fortunately, his roots are strong enough.

After extending into the flame, absorb all the core flames inside.

For a while, Chu Nan's body grew rapidly under this terrifying growth speed, gradually growing from seven meters to nine meters!

It was also at this time that ......

He has finally reached the end of the second stage!

"Phase 2...... And how to break through?"

Chu Nan pondered this question in his heart.

He had thought about it before, and he had some ideas in his heart, but he wasn't sure if his idea was feasible.

For now, I can only try it according to my own ideas.

And the way he thought of it......

It is in the body that condenses a flame similar to that underground!

However, the power he used to condense was not to condense with hot air, but to ...... Tree Power!

"With the power of the tree, condense the tree fire!"

Chu Nan's thinking is very clear.

Now there is a lot of tree power in his body, which is far from being comparable to when he first broke through to the second stage.

Under his control, these tree forces coalesced together, imitating flames made of hot air.

Earlier, while absorbing the hot air, he had also carefully observed the entire structure of the flame, and it was precisely because of his observation that he had such thoughts.

For a while, the tree power in his body continued to condense.

But after condensing to a certain extent.

Airplanes!

These tree forces suddenly became unstable.

"Oops. ”

Chu Nan secretly said that it was not good.

Rumble!

The power of these trees, which had just been condensed together, suddenly collapsed.

Chu Nan frowned, falling into deep thought, feeling as if something was missing.

After some thought, a flash of inspiration flashed through his mind.

"I know what's missing!"

"I don't have Core Flame!"

It dawned on him.

The flames he absorbed earlier all had Core Flames, and now that he wanted to emulate these flames, he naturally had to have Core Flames as well.

As for the choice of Core Flame, he already had an idea.

"Just use the heat sphere in my body as a ...... Core Flame!"

Chu Nan's heart was filled with anticipation.

In this sphere of thermal energy, there is red yang thermal energy, and the two are not only not in conflict, but extremely suitable.

Immediately, Chu Nan used the thermal energy ball as the core flame, surrounded it, and condensed it with the power of the tree.

After having the core flame, Chu Nan suddenly relaxed a lot in the condensation of the tree fire, and there was no longer the previous unstable situation.

However, when it was about to be completed, there were still fluctuations, and Chu Nan immediately became nervous, held his breath, and handled it extremely carefully.

After some condensation, it finally ......

He accomplished his inner thoughts!

A tree fire condensed in his body.

This tree fire is completely condensed by the power of the tree, surrounding the thermal energy sphere, with the thermal energy sphere as the core.

And at the moment when this tree fire was formed.

Chu Nan's entire body suddenly underwent a transformation!

The bark on his body cracked, and as it continued to crumble, it fell off and grew new bark again!

The newly grown bark, black and shiny, made his trunk look as smooth as a mirror.

His branches and leaves were also shiny, and they looked unusually bright.

Even the roots of the trees are dazzling.

In addition to these superficial changes, there was also a huge improvement in all aspects, filling his entire body.

"I made it!"

Chu Nan's heart was very excited.

Everything was as he had guessed, and this was indeed the way to break through the second stage!

Now he has officially entered the third stage from the second stage!

The most terrifying thing is that it took him less than a month to reach the third stage!

Even if he didn't know what other people were doing in the trial world, he could feel that his speed had definitely surpassed many people.

If it weren't for the time of his trial, later than those people, he even felt that he had the hope of hitting the first!

With the breakthrough to the third stage, after having a comprehensive improvement, Chu Nan decided to continue to spread towards the underground of the ancient castle with the roots of the tree.

He was curious to know......

What is there under this ancient castle?

For the fourth stage after the third stage, he has no hope left.

Because the growth of the third stage has reached an extremely terrifying level, it will take a long time before there is any hope of breaking through the fourth stage.

Even if there is a lot of heat here, as well as the core flame, according to preliminary estimates, it will take at least three years!

And the time flow rate of this trial world, although it is different from the outside world, Chu Nan has spent more than ten or twenty days here, but he doesn't think that the time flow rate here will be large enough to support him to stay here for several years.

In fact, he's already feeling something strange these days.

Occasionally, the vision may be blurred.

He realized......

This may be a sign that the trial is coming to an end.

His time here is running out.

Now he just wants to use the last time to explore the underground of this ancient castle.

Earlier, Chu Nan might have been worried that his roots were not long enough, but now after breaking through to the third stage, he no longer has such worries.

At the same time, the sharpness of the roots of the tree is like a thorn on the soft tofu when it is pricked in these rocky soils, and it is easy to break it.

As we get closer, it's a world of flames!

Many flames were burning, and the heat wave was monstrous, but fortunately, Chu Nan had successfully broken through to the third stage here, and he was able to withstand the scorching of these flames.

"Could it be that the bottom of this ancient castle is a sea of fire?"

Chu Nan vaguely felt that it would not be so simple.

Look around.

Suddenly......

In the midst of the fire, he saw a huge chain!

Under the burning of the sea of fire, this chain stretched all the way up, with no end in sight.

Chu Nan's heart moved.

Feeling the extraordinariness of this chain, he immediately controlled the roots of the tree and changed the direction of extension, no longer extending forward, but upward.

Whew!

In the process of the continuous upward extension of the roots of the tree, this chain was also clearly seen by Chu Nan, this chain was at least fifty or sixty meters thick, I don't know what kind of material it was cast, even if it was burned by these fires all year round, there was no damage.

After a company extended upwards for hundreds of meters.

Finally......

Chu Nan saw the end of this chain!

This chain......

It was connected to a blue earth.

"That's not right...... This is not the earth!"

Chu Nan looked at the broad cyan above.

"Is this the bottom of the castle?"

Chu Nan's heart was filled with speculation.

He found that these seas of fire were completely suppressed under this cyan.