A few hours later, Aito and his team finally reached their destination, a small plateau on top of the lonely mountain on the fourth floor. 

The climb could have been rough for normal humans. To them, it had been enjoyable at worst. 

Thanks to her passive skill Parkour, Sheyla had been the first to reach the top ten minutes before the two others. Aito and Ogoro couldn't be called slow. Climbing a one thousand two hundred meters mountain in less than twenty minutes with all their gears wasn't slow at all. 

Once up there, they established a small camp. Well, if settling their backpacks on the ground could be called a small camp.

They were planning on waiting until after CD to get to work so that fewer challengers would bother them because some, motivated by greed or the need to feed themselves, might just be brave enough to stay here after CD

Aito had chosen this spot for a few reasons. First, because it allowed them to see the whole floor. From the forest, it seemed endless. However, it just spanned over fifteen kilometers' radius. Probably as large as the island he had been on. 

Second, they could more or less keep an eye out for other challengers, particularly with Sheyla's gift. Her enhanced vision came in handy while scouting from a high place. They had shared their abilities amongst themselves, so they knew what each other was capable of.

Aito had already known about theirs thanks to the candle, though. He had also kept a few things hidden from them. 

The third reason for their coming here was the secret entrance to the labyrinth of tunnels inside the mountain housing many goblins, which directly led to the heart of the mountain.

It wasn't a particularly obvious one to find. Bushes, trees, and a huge rock hid it from plain sight. No one had found it until now, probably also because no one bothered coming up here. Even if they did, noticing something that blended into the vegetation quite well wasn't so easy. Unless one already knew about it, it could be tricky to find the entrance. 

Aito planned on using it later after CD to enter the tunnels and hunt the special goblin hiding inside. Few challengers dared venture in there because of how messy the tunnels were, even fewer dared going deep enough, thus the special creature's existence had been kept a secret until now. 

As for what kind of reward it'd bring him, he didn't know yet. All he knew was the rewards for clearing the fourth floor.

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[Fourth floor's quest: Hunting small but green]

Quest: Kill 40 goblins yourself in one day. The number of goblins killed will reset after 24 hours have passed. 

Enemies: Goblins are small green creatures. They aren't smart, nor stupid. Underestimating them could lead to death. Goblins lack bravery and find courage in their numbers. It isn't an uncommon sight to see some of them running away when the situation seems hopeless. Be wary of their ambushes. 

Difficulty: Easy or Normal (Based on the average ability of a Challenger) 

Rewards:

- Access to the Fifth floor

- 100 glory points

- 1000 Tutorial Points

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Apart from clearing the quest, killing one goblin or apparently any other creatures brought no TPs. For that, one would have to collect the soul cores and sell them on the second floor. Aito theorized it was to force the challengers to go back to the Mall at some point during the day or increase the Tower's difficulty. 

Why? Maybe for training? He didn't care, it was the gods' scheme so that didn't matter to him. 

Aito stood in front of the rock blocking the entrance to the underground tunnels, examining it. 

Meanwhile, Sheyla was busy scanning the entire floor with her enhanced vision, familiarizing herself with the area. With her level up, her gift allowed her to see 1km away as if it was just in front of her. With time, she learned to adjust it. Zoom in and zoom out. Pretty useful to avoid headaches. 

Down there, in the forest, she could see challengers fighting the groups of goblins that started to dwindle. After two months, the survivors had adapted and could kill the green creatures relatively fast. Soon, the forest would be deprived of them. It would force the humans to venture underground to find more.

With nothing better to do, Ogoro trained his new class skills, switching between making shallow cuts on one of his arms to sew it back together and grabbing random stone he sent flying with his binding string. 

Binding string was quite tricky. It felt like a "foreign" part of his body was projected outward. However, he quickly found a way to control it, thanks to his enhanced sense of touch. Like Sheyla, he had learned to regulate the output to avoid uncomfortable situations. Currently, he was just trying to familiarize himself with the skill so that he didn't have to use his gift with it. 

While his allies were training and also keeping an eye out for potential trouble, Aito placed a hand on the rock blocking the secret entrance. It felt rough to the touch, but also weirdly smooth.

There were a few ways he could get rid of it. One of them was to destroy it using the pickax Ainar had given him. However, he wanted to take this opportunity to train and acquire the skill that had been passed down to him through the memory bead. 

According to the memory, the warrior class active skill Impact used aura to channel one's striking force into a larger area of impact. 

For example, when a warrior used this skill when punching a wooden dummy, instead of simply destroying the area where their punch hit, it would destroy the whole dummy. Much like what Gwen had shown during their first encounter. 

Its power relied on the fact that it would spread the power of one strike to an entire area. 

Simply put, if Aito were to concentrate all his strength on a single point of a wooden dummy, it would replicate the same strength in every inch of the wooden dummy's body targeted area.

With a weapon, this skill could be devastating. Even more, if the weapon was a pike, the strength of the wielder would be focused at the tip, increasing the penetrative power. 

Aito focused on his soul core at the center of his bosom. More accustomed to aura than before, he rapidly made it travel to his hand and applied a little pressure on the rock while discharging his aura with the image of a shock wave in mind, trying to shape the aura accordingly.

Nothing happened. 

'Yeah, figured it wouldn't be so easy.' 

Second try. 

Nothing.

Third try. 

Still nothing. 

An hour, some rest, and a few mana beads later. 

As Aito applied pressure to the rock, a shock wave spread in a round arc encompassing a surface area of fifty centimeters. 

[Congratulations! You have acquired the new active skill Impact Lv1!]

'Thank you, memory bead!' 

Although it took some time, he finally acquired the skill. Like when he had first acquired Durability, he couldn't use it instantly. However, thanks to his training, he was more familiar with the use of aura than before. He estimated that it shouldn't take him too long to get to that point. 

In the meantime, something else bothered him. The rock hadn't cracked nor budged one bit. He used Impact again, but instead of a simple palm pressure, he struck the rock with a punch. 

Nothing happened. 

Confused, Aito tried the skill on a nearby young tree only to blast off the targeted area to pieces. Hanging by a thread, the tree fell with a moderately loud boom, alerting the two siblings who turned towards him. 

He gestured that everything was okay, as if a tree falling with a punch was normal, then pondered what was wrong with the rock. 

Taking into account what he knew of the special monster hiding at the heart of the mountain, a ridiculous but plausible possibility popped up. 

Aito waited for the siblings to return to their training then activated Fearless Aura. His body glowed in yellow light, much denser and brighter than when he used Durability. When his hand came into contact with the rock, its surface rippled, then the entire rock disappeared to reveal an entrance to the tunnels. 

"Open sesame," Aito said, with a satisfied smile on his face. "Guys, the way down is opened." 

"Did you break that rock with your pickax?" Ogoro asked, walking close to him. 

"No, it was an illusion placed on the entrance." 

"An illusion? Suppose I shouldn't be surprised with all the magical nonsense in this world. Did Gwen tell you about it?" 

"I didn't know at first," Aito replied. "Gwen gave me info on the floors, but I suppose she left out a few things on purpose. It was a simple deduction considering the creature hiding in the underground tunnels." 

"You broke the illusion?" Sheyla asked. 

"Yeah, sort of," Aito replied. Realizing he was too vague about his answer, he added, "Nothing brute force can't handle." 

She stared at him suspiciously, appearing to doubt his answer, but didn't say anything to inquire further details. 

"Brute force can be useful sometimes, I guess," Ogoro said, seemingly overly trusting. "We're going in now?" 

"No, I need to rest first to replenish my supply of mana and soul power. I also would like to try to absorb my share of the soul cores we've collected until now." Aito replied, "We'll be heading in once it gets dark." 

Compared to the first floors, the fourth floor and above had real night times. It got darker after CD, making it harder to fight the goblins that were small enough to camouflage themselves in the dark. 

Meanwhile, unbeknownst to them, Sleon, the moderator of the fourth floor was eyeing the group from above with a curious face—as curious as his usual unexpressive face would allow him to make. 

Floating in the air thanks to strings invisible to the naked eyes, he flew away to rescue wounded challengers who had been fighting amongst themselves.

Weirdly enough, more challengers died by fighting other humans than fighting goblins on this floor. 

When they didn't venture into the tunnels, that is.