Summoned with an SSS-Rank Portal Skill

They walked toward a collapsed tower. It was one of the few structures in the sunken city that was destroyed like that. Most of the others were still in decent shape.

"Inside here is where I mentioned there's a different area of the city, something that could be useful to us," the adventurer said.

William looked at the tower's entrance — a door that was hard to reach exactly because the tower had fallen sideways — and then said, "Are you telling the truth? We're gonna have a problem if this is some kind of trick…"

The place looked strange to William. He would have to crouch and crawl into a collapsed tower. That was weird.

But the adventurer stomped the ground with confidence, swearing he was telling the truth. "I'm serious. I'll go in first to show you."

Before they entered, William asked one more thing. "If this is the place you think might have treasure or even the portal to the next floor of the dungeon, why were you guys just standing around outside, and not exploring it?"

That question was key to understanding those adventurers' true motivation. William had a few guesses, but he wanted to hear it straight from the guy's mouth.

"We explored a small part, but it started getting real dangerous. So we were taking constant breaks, but we didn't want anyone else going inside. That's why we tried to kick you guys out," the adventurer said.

That was exactly what William had been thinking. If it were him, though, he might've used a different tactic. Maybe letting others go in first to trigger traps or learn about the monsters below wouldn't have been a bad idea.

Anyway, the three of them went inside the tower. The adventurer went in first, followed by William, and last was Rena, who seemed lost in her thoughts as she followed behind.

They had to crouch down to squeeze through the door. It was tough.

Right at the entrance, they were met with something interesting: a staircase leading downward. They descended, and William was met with something rather strange...

What he saw was something completely unexpected. He found another city below. It was like they had stepped into a different world.

"This is so weird," he said.

When William looked up, he didn't see the staircase they had just come down. Instead, he saw the exact same view of the city as before. It was like an inverted world or something similar.

He was certain some kind of magic was involved, because he had only gone down a staircase and didn't feel any sort of dimensional shift.

"I think we passed through some kind of portal on the stairs. That's the only explanation," he said.

Anyway, the city they found down there wasn't exactly the same. Even though the size and layout were similar — nearly identical, really — the buildings were made from different materials.

Another important detail was that the houses were more damaged, more ruined than usual.

What immediately stood out was a massive castle sitting at the highest point of the city. It was made from a dark-colored stone, not black, but rather a deep violet shade.

That castle was in excellent condition, looking practically new, and it was still lit up — the complete opposite of the rest of the city.

"I think the portal must be there," William said, pointing to the castle.

The adventurer nodded. "Yeah, that's where we were heading, but there are different kinds of creatures down here. More dangerous ones. You'll need to be careful moving around this place."

William laughed. "You mean we need to be careful, right? Because you're coming with me."

"But I thought you were gonna let me go if I told you the truth?" the adventurer said, frustrated.

"I will — if you survive the creatures down here. Come on, we need to reach that castle."

There was no reason for William to be generous with the guy. Having him around would be a big help, since it was another person to fight the creatures down here.

Not to mention, he had some experience exploring the area already — all upside for William.

Rena, who still hadn't said much, walked up beside William and said, "This place gives me a bad feeling."

William felt the same way. It was like a sense of death, an ominous foreboding.

"Yeah, it really does. But we'll be fine," he said, smiling and placing a hand on Rena's arm. "I'll make sure you stay safe."

They were determined. Their goal was to reach the castle, but to get there, they'd have to deal with some rather strange creatures.

Zombies. Yes, zombies. It didn't take long for William to spot a group of them heading their way.

But these weren't your typical zombies like the ones you'd see in a TV series. These were warriors, mages—people who had somehow been turned into undead!

That made them way more powerful than usual. They wore tattered clothes or damaged armor, and carried various types of weapons.

The most impressive part was that they could cast spells too! However, their casting was slow. That gave William and the adventurer enough time to react against them.

"Ever killed one of these before?" William asked.

"Yeah. You have to aim for their heads, and if you use any kind of fire magic, the damage gets a big boost," the adventurer replied.

Aiming for the head was obvious to William, but the fire magic detail was a pleasant surprise. No longer in his transformed state, he sprinted toward the zombies.

On the way, he channeled his demonic energy into his sword, forming a dark aura around it. This aura had black fire properties—making it extremely effective against the undead.

William dashed through the stone streets, his footsteps echoing against the ground. He had to dodge potholes and broken terrain as he moved.

Before he could reach the zombies, one of them managed to finish casting a spell. The magic was disgusting. A cloud of rot appeared in the air, floating toward William.

The cloud was filled with blood, entrails, and a thick black fluid. Even with his strong body, William didn't want to get near that mess. Just the smell was enough to make him nauseous.

He activated one of his body enhancement skills, boosting his agility by 50 points and increasing his movement speed by 20%.

Right now, power wasn't what he needed—he needed speed to dodge that foul cloud. And he succeeded.

The cloud was slow compared to William. It splattered across the city ground, unable to hit him.

As soon as he reached the zombie, gripping his sword tightly, William landed a swift, precise strike to the creature's head, slicing it clean in half.

The sword's fire property boosted the damage, burning the zombie's entire body. The creature died instantly.

But when William looked to the other side, he saw more than 30 zombies approaching—and one of them was different. One of them was a massive flesh golem, over five meters tall…