Without having to worry about being surrounded by enemies or looking for dangerous monsters, Leon and Darya found the boundaries of the continent after flying for a few days. Just as Leon had imagined, that massive layer of earth that was the soil of the city above extended until the ocean. It was weird since Leon didn't see any signs of mountains... perhaps the battles of the past destroyed the world more than Leon had imagined, or maybe the people of the city above destroyed those in order not to build the city so high in the sky.
Even from afar, Leon could sense the smell of the ocean. It wasn't much different from Earth. The poison mist was thinner, but there were signs of patrols and battles everywhere. Some of the metallic pillars that sustained the city were also partially destroyed. Even though Leon was quite confident that he could cause some damage to those pillars, he was also sure that he couldn't put them in the state they were.
"I guess the best option is to dig a hole and create a path under the earth," Leon said.
"What are we going to do once we reach the ocean?" Darya asked. "The pressure of the water will push us backward, and even if we manage to endure that, we will run out of air."
"We will manage using Mana Barrier," Leon explained. "Before that, we will level it up as much as we can. That way, the barrier will be bigger, and we will have more room to store air and cross the ocean. If I use some mana potions, I will be able to decrease our weight using the ring of gravity and ring of telekinesis."
"So, you have those too?" Darya asked. "I'm pretty sure gravity is the type of magic that can make our soldiers fly. Didn't you learn yet?"
"No," Leon answered. "... I should have asked for that kind of information since even ordinary guards can fly and use telekinesis... maybe it's not too late, I just have to capture one soldier or a guard and ask 'nicely' for information."
"You should give up on that," Darya frowned. "Our soldiers are pretty united, they get angry when a fellow soldier dies, but if one is taken as a hostage to be tortured, they will become even madder and probably chase until you or then die."
"... I guess I will do that once I have a little more faith in my skills." Leon said.
After that, Darya started to practice Mana Barrier. Meanwhile, Leon began to dig the hole. Instead of creating and using some shovels, Leon just infused his mana on the soil and moved it. They were like three kilometers away from the ocean, and Leon also had to be careful while digging, otherwise they could be buried. Still, Leon didn't complain since it was a simple, but efficient way to practice his earth magic.
Two days later, Darya finally learned the spell. So, Leon stopped digging, and they attacked each other's Mana Barrier. Although they were in a hurry to strengthen the spell, they only used Wind Bullets because it was silent, and the sound of impacts was barely noticeable.
They practiced for one week because Leon only felt satisfied when the Mana Barrier was big enough to store five minutes of oxygen. The hole was almost complete, and both of them were ready to put the plan in action, but they were forced to stop when they felt some earthquakes.
"... It looks like one of them appeared here." Darya said, her face was pale.
By them, Darya was probably talking about the harvesters. The ground below and even the one who sustained the megacity above them was trembling. In the distance, Leon saw the sea, but he also saw the lower body of a creature that had several parts of his body engulfed in flames.
"Are you for real?" Leon frowned.
"… It is the fire titan." Darya said. "One of the most troublesome and powerful harvesters that attack our planet. We don't know his name, but we do know he can absorb that fire attacks, and we don't have a soldier who is powerful enough using water or ice magic to even scratching him."
While Darya was giving her explanation, Leon felt the temperature rising. That was absurd, they were three kilometers away from the creature, and they could feel the heat emitted that thing's body. Leon couldn't even imagine how soldiers could withstand the heat, much less fighting against the one hundred meters tall fire titan.
Darya's Fire Resistance was still low-level, so she almost collapsed due to the heat. Fortunately, Leon reacted on time to make the surroundings fresher by combining wind and water magic. Still, it wasn't a good idea to continue with the plan, so they retreated a little and waited for two days until the earthquakes stopped, signaling the end of the fire titan's rampage.
"... He sure has a lot of energy to keep causing earthquakes for two days straight." Leon frowned.
"Do you still feel like challenging one of them to obtain the information you want?" Darya asked. "I don't know about the harvesters that attack other worlds, but the ones who attack us are all giants like him."
"I won't change my mind." Leon declared. "It is clear now that the world of that dungeon is a world that got assimilated, but its sentient being didn't survive assimilation. So, it is a waste of time to search for any useful knowledge in those places... the quickest way for me to go home is to ask those colossal creatures how they can travel between worlds without using dungeons."
"Even if you learn that I don't think you would be able to replicate," Darya said. "The difference in power, resilience, mana... is too great. Even we, who are a race that decided to increase our powers using mana alone, have little mana in comparison to them."