Castle of Black Iron

The first abyss in the earth-elements realm was the main battlefield of human knights and demon knights.

Demons were constantly pouring out of the hollow earth; if they wanted to arrive at the land of the Eastern Continent, they had to break through the Lion Fortress.

As for Taixia Country, the holy war had two battle lines which were undergoing at the same time.

One was in the first abyss in the earth-elements realm; the other was in other continents and subcontinents from where demon corps were constantly pouring out of the earth surface from the underground world.

As for demons, this holy war also had two battle lines. Demons' attack on the earth's surface could be regarded as a siege of Taixia and the Eastern Continent while their attack in the earth-element realm could be regarded that they were going to collapse Taixia Country from inside.

The two battle lines were both fierce, which could be judged by the increasing treatment that those chaotic subcontinents and the Lion Fortress could provide for the garrison knights.

Compared to the battle line on the surface of the ground, the underground one was fiercer and more brutal. Those who could fight demons in the first abyss were at least human knights, human battle spirits were too weak there.

If the earth's surface was predominated by humans, the underground world was predominated by demons.

The first abyss was very huge that nobody could figure out its border. Generally, the word "huge" referred to the area; however, the first abyss was like a deep well in the earth-elements realm.

The part outside the irregular mouth of the well was over 14,000 miles in width and above 40,000 miles in length.

Zhang Tie received the data from the Lion Fortress. He didn't verify it and didn't need to do that.

Of course, the wall of the well was not smooth. A small grain on the wall of this well might be an exotic region that covered thousands even tens of thousands of square miles; a small coarse bulge on the wall of this well might be an endless mountain range. The profound and deep mountain caves in the first abyss were like the holes on the bricks and slabs, which might lead to other abysses and mysterious lands...

From a certain perspective, the first abyss was more like an open courtyard in the middle of an irregular tube-shaped apartment. There were overlapped platforms, large or small and interconnected maze-like rooms, tunnels and bloody traps in the dark around the courtyard.

After leaving the Lion Fortress one day, Zhang Tie caught sight of a pitch-dark, borderless abyss which looked like a black, huge mouth which could devour everything.

Zhang Tie saw rolling, dense fog in the endless black abyss.

As there was no light inside the abyss, it was more like a black fog.

Some human knights were flying out of the black fog while some flew in. All the human knights had decelerated their flying speed the moment they entered it while they hid their battle qi luster.

It was nothing different than committing suicide by releasing one's battle qi luster like a bulb in the dark of the first abyss.

Besides a lot of black iron knights, many earth knights were also wandering in the first abyss. Even though shadow knights were hiding there. It was not strange if human and demon heavenly knights had passed through the first abyss accidentally.

Of course, Zhang Tie didn't want to show off his battle skills at this moment. He hid his battle qi luster and entered the dark closely along the edge of the first abyss.

...

As the black fog was ubiquitous, even in his maximal dark visibility, Zhang Tie could only see a few miles forward in the first abyss.

A strange plant covered many places on the ground and the precipices in the abyss.

It was an exotic vine-like creeper which could grow endlessly in the first abyss.

Any common vine of the abyss could extend longer than 1,000 m. The longest one could even extend over 70 miles. In Zhang Tie's eyes, the leaves of the vines were deep purple; each leaf was as large as a pot's cover. Its flower was extremely similar to a necessary musical instrument in the human symphony orchestra——tuba! The fog in the first abyss was released by the flowers of the vine of the abyss in a breath.

The fog purified the strong sulfury, the particulate matters and some toxic substances in the air and provided a necessary condition for the growth of other living beings in the abyss.

Even in the first abyss, the living beings complied with some universal rules of the mother nature——without the plants that could grow out of the earth, none of the senior species would survive.

The moment Zhang Tie entered the abyss, he had caught sight of a finger-sized bee hovering on the flower of the vine of the abyss diligently.

The honey of this bee of the abyss was inedible. It contained a special toxin, which would make people feel especially itchy all over. Those who were allergic to pollen would lose their lives the moment they touched the honey of this bee.

After deepening almost 30 miles into the first abyss, Zhang Tie caught sight of a mountain cave behind a vine of the abyss. He then entered it...

After a few minutes, a little, black beetle flapped its wings and flew out of the same mountain cave and dove downsides in the effect of super hiding skill...

30 miles were like a step downwards from the top of a skyscraper.

...

After 10 days, on the land that covered 700 square miles in the first abyss.

A huge demon knight with double horns landed in the fog.

Its eyes were as red as fire which looked very vigilant. After landing there, he looked around seriously. After finding that no human knight was in the surroundings, it darted into a wood.

The wood was filled with a giant underground plant which looked like a bamboo shoot.

After coming to one side of a plant, the demon knight checked his alert arrangements within 100 m and confirmed that nobody had come here. He then let out a sigh. After unveiling a cave on the plant, it hid in.

...

The long-term battle in the first abyss meant a great test and physical strength consumption for both demon knights and human knights. They could not fly in the sky around the clock. Even knights needed to take a rest. Otherwise, their battle strength would decline sharply after staying in the first abyss for too long.

This wood was one of the demon knight's shelters in the first abyss.

The demon knight didn't notice that a little beetle which was having a rest on another tall plant had caught sight of him the moment he entered this wood...

...