In the fortress, the troops tasked with guarding were patrolling in many parts of the fortress. They were on the defensive wall or inside the fortress, patrolling between the still-standing buildings. The others who were not tasked with guarding were doing their own things such as cultivating or simply sleeping.

The situation was quite peaceful, allowing some people here to relax their mind after battling all day. However, the peaceful atmosphere of the troops was suddenly disturbed when Aldrian's voice transmission came to each individual.

"We have visitors. Prepare for battle, but don't make too much noise. Once all of you are ready, I want you to spread across the fortress to greet our visitors."

The moment the troops heard that, many stopped what they were doing and followed Aldrian's order. They knew Aldrian was not talking about normal visitors, and "greet" here meant they would have to battle again. But they were confused about why Aldrian asked them to be quiet in their movements.

Aldrian then told the troops about the devils that were about to launch a surprise attack, which made the troops surprised, but it was still within their expectations. They knew the devils might be planning something when they saw the empty fortress. They were already prepared for anything the devils might do.

They had to move quietly so the devils in the underground would not detect anything strange on the surface and cancel their attack.

Aldrian guided his troops to several places where he thought the devils would appear on the surface. He could clearly sense the devils getting nearer, and he could guess where they would appear.

After more than fifteen minutes, the ground in many parts inside the fortress slowly opened, creating holes for the devils to come out. The devils did not instantly come out as they were checking the situation first.

Because Aldrian also ordered any light to be put out, the scene was really dark. However, the devils that saw this found nothing strange, as it might be one of the enemies' procedures to not use light while they were in hostile territory.

The devils could still see in the dark, and they found nothing strange when they only saw some of the guards moving here and there. They did not spread their spiritual sense so they would not alert the enemies.

After making sure there was no problem, the devils started to come out from their holes one by one. The leader also came out, but the moment he appeared he instantly sensed something was wrong. He stopped his movement and looked at the silent surroundings. He narrowed his eyes before suddenly widening them.

'Shit, this is a fucking trap!' he thought before he shouted.

"This is a trap! Destroy everything around you!"

However, his warning came too late, as the Aster Empire's troops were already attacking the devils that had already stepped onto the ground. The dark place was instantly lit up with fire elements and other elemental strikes.

The leader, who also wanted to strike with his mighty power at this moment, could not do anything. That was because right after he shouted, Aldrian had already teleported his body into his grasp and instantly fried his head using his heavenly lightning.

The leader, who did not expect to suddenly fall into Aldrian's grasp, could only feel pain spreading across his body, especially his head. He could not move, as his soul was shaken greatly by the heavenly lightning strike. Moreover, combined with the golden energy, which was their weakness, it was the same as a curse for the devils.

Not even ten seconds passed before his resistance stopped, though his body still spasmed because the heavenly lightning was still flowing through him. The moment Aldrian stopped his attack, the devil leader's head had already turned into charcoal. With a slight grasping motion, his head instantly crumbled, and his body fell down from the sky.

Aldrian did not stop after killing the leader. He continued to attack the devils from the sky as he used his lightning laws. His strikes were precise, targeting the stronger devils who had middle pseudo immortal foundation cultivation and above.

The silent night became chaotic, and the devils who had already come out started being slaughtered here and there. They did not expect to be ambushed.

The devils still underground, knowing that their surprise attack had failed, decided to retreat.

"Fall back, fall back! We have been found out! We are being slaughtered out there!"

"Go back! Go back! Quick!"

Many devils urged their comrades behind them to retreat. Because their underground path was small, only large enough for one person to move in a line, those in front needed the people behind them to retreat first. If not, the ones in front would be stuck. That was why the foremost devils urgently told the ones behind them to retreat quickly.

Watching their comrades on the surface getting slaughtered, they knew it was only a matter of time before the enemies redirected their focus to the ones still underground.

True to the devils still in the underground's guess, their worry and fear became reality. The troops who had finished taking care of the devils on the surface switched their focus to the ones still underground. However, because of the narrow passage, they could not battle properly, as they could only attack the foremost devil.

There were still thousands of devils underground, and all of them started escaping much deeper into the underground and out of the hill area. This caused Aldrian's troops to feel frustrated because they could not do anything due to the terrain. They also could not pursue them individually, because that would be the same as suicide.

Individually, they would be weaker than these devils.

However, they then saw Aldrian appear beside one of the holes, and from his hand, a spark of flame appeared. The flame intensified with his golden energy, which made its heat grow hotter, and Aldrian used the power of his domain to make it much stronger.

The flame's colour slowly turned to blue, and it made the people near him step back. That was because even the heat alone gave them goosebumps, and they instantly started sweating just from the thought of getting close to it. The flame was enough to kill even someone at peak pseudo immortal establishment with ease.

"Everyone, take a distance from the holes!" he announced to his entire troops. They instantly obeyed his order and moved away from the holes where the devils had come out.

Aldrian then looked at the hole on the ground beside him and directed the palm that was still ignited with flame toward it. A moment later—

Whoosh!

The flame burst with great power toward the hole. A strong gust of wind was pulled into Aldrian's direction as the oxygen and the surrounding energy seemed to be sucked toward the flame to strengthen it. The flame instantly swept through the underground path at high speed.

The devil positioned at the forefront of the hole that Aldrian struck saw the sudden light coming from the surface. It happened so fast that he still had not registered what the light was when the flame swept through his body and the ones behind him. He only felt a sudden burning sensation and pain before his sight turned to darkness.

His entire being turned to ashes as the flame swept through him and continued behind him all the way to the deepest underground path. The flame filled all the paths, and it instantly came out of every hole the devils had created as passageways to the fortress. Pillars of blue flame burst out, making everyone cover their faces to shield themselves from the heat.

The flame in the underground paths killed thousands of devils in a short time, and it even filled the path leading outside the hill. In the distance, a rumbling sound of an explosion suddenly erupted as the flame burst to the surface.

This was the gathering place of the devils before they moved toward the fortress. The underground area collapsed, and the flame burst upward, and from the fortress the troops could see it in the distance.

After a few moments of unleashing his flame, Aldrian finally stopped and looked at the hole that was still slightly burning. He then heard a rumbling sound from deep underground and felt a slight tremor. The hole crumbled and closed itself as the underground paths collapsed. The rumbling and tremors continued for a few seconds until everything finally fell silent.

Seeing and sensing that nothing was wrong, Aldrian then gave his order.

"Good job, everyone. Now you can clean the aftermath of the battle. There are no devils that will disturb us for now."

The troops did as he said and began to spread out to clean the remnants of the battle. Aldrian then landed beside Baek Jimin.

"Those devils were really planning something, and thanks to you we could break their plan. I was truly amazed at how you could sense something deep underground even when you looked relaxed in front of me," Baek Jimin said with a smile.

"Well, what can I say? I just happened to have sharp senses, and you could sense it too if you reached my level," Aldrian replied. He would not say that the devils moving underground had entered his domain, which also extended beneath the ground and allowed him to detect them.

They continued to converse and enjoyed their time together after the devils' visit had disturbed them. For the rest of the night, there was no further disturbance until the sun rose.

Aldrian and his troops then continued their conquest journey an hour after the sun came out from the horizon.