The staircase was akin to a stone tube, plunging deep into the ground. Only after he’d traveled a few dozen feet downward was there finally a change. The staircase continued deeper, but there was a door frame that led outwards. There was some wreckage blocking the door, but it only took him a few moments using Foresight to determine where to cut in order to clear it all. He tossed it all into the Inner World and stepped through the doorway to explore.

As he expected, there wasn’t much of note, considering the passage of time and the wrecked state of the place. Those who destroyed the place would have looted it before leaving so it was no surprise. He collected anything that wasn’t nailed down and it was this thoroughness that led him to a discovery. An air vent. He found a sort of grate with air flowing from behind it. It wasn’t really a big deal until he returned to the stairway and found the path forward blocked. No matter what method he envisioned, it led to a full collapse of the staircase in his Foresight. The rubble was placed ingeniously in that it was holding the place up and also blocking the way forward.

To get through he’d need to carefully reinforce it while digging, which wasn’t outside of his capabilities, but he chose to try the path of least resistance first. The air vent he’d found was pretty large, but not very comfortable for him to squeeze through. That is of course, if he wasn’t from the Lang Clan. He spent a few moments linking to a fresh Steel Silk Centipede and then entered the insect’s inner space. Using acid and its sharp forelimbs, the centipede carved a hole into the grate and skittered into the foot wide tunnel. He attached a silken line at various points along the tunnel and used it to rappel downwards, finding that the vent led down deeper.

Soon he ran into a few side tunnels that also led to grates. Ones which he sliced through and hopped out of the centipede to investigate. The second floor was similar to the first one, but by the time he reached the third he was surprised to find signs of life. A type of phosphorescent mushroom and moss were growing on the walls and floors. It wasn’t one that Sage specifically recognized, so he sent some to the Inner World for testing while he continued to explore. Along the way he encountered a few small insects and lizards, taking a few of them as well. The ruins of the sect were just as battered as the first two floors, so he went into another vent to keep descending.

The fourth and fifth floors had more of the same, but with two notable changes. The size of everything seemed to increase. The mushrooms were now bigger than his head and the bugs and lizards were larger than cats and dogs. He took samples of them all as before, especially because the other difference was far more unusual. The air from the vents was constant and it was only now that he’d gone this far did he notice what was going on. There was a considerable increase in the ambient air pressure. Due to his strong body he hadn’t really noticed a difference, but now that he’d descended deeper and the pressure increased it was quite obvious.

After just a few moments he was pretty sure this pressure difference would be enough to kill normal humans quite easily, but not because of the pressure itself. The true danger was actually the air he was breathing. When the components of air are pressurized to a certain degree they become toxic. He wasn’t really sure about the specifics, but he had of course heard of ‘the bends’ and the danger divers faced when descending too deep under the sea. Sage wasn’t under the sea at this time, but this place exerted extremely high pressure upon him. Even so, it wasn’t very difficult for his body to resist, it was only really apparent when he breathed in.

Thankfully, he was a powerful cultivator and the most foundational cultivation techniques were breathing techniques. He could easily filter the energy that he required from the air and didn’t need to just survive on oxygen. Or at least that’s what he assumed. He had no idea how to start studying air molecules from scratch. He’d never figured out how they do that back on earth, but he was able to breathe with a little difficulty so he wasn’t concerned.

On the other hand, the little centipede was not so lucky. After a few minutes on the sixth floor he heard a crack and the thing died before he could even send it away. Studying the anatomy of insects was a far simpler topic and on the Inner World he discovered that its tracheal system, was what they use to ‘breathe’. Unlike mammals that use their lungs to filter oxygen and feed it to their circulatory system, the tracheal system is separate from the circulatory system. They use tiny holes, spiracles, to introduce air into their trachea which then distributes the oxygen to their whole body. Rather than an air processing plant, the tubes and airlocks inside their body are more like a spaceship keeping pressure equalized and evenly distributed.

The great pressure in here overwhelmed the bug and its tracheal system was ruptured. Facing this new problem, Sage used one of the local insect species as his new vessel, linking with one of them and using it to carry him down into the next floor. Each floor these creatures got larger and tougher, which he assumed was to help them cope with this strange environment. At the same time, he wondered how being larger helped against great pressure. Wouldn’t that only make them suffer more pressure? Then again, whales are huge aren’t they?

The seventh floor was far more terrifying than the sixth and the pressure was suddenly exponentially higher. The insect he’d got from the sixth floor was struggling and he had to send it away. It became somewhat difficult for him to breathe in here, so he simply stopped for a while. There were more than a few techniques that helped cultivator’s overcome the limits of the body and more than a few hermits that lived at the peak of absurdly tall mountains for years. They went without breathing, eating or drinking, converting Qi into all the energy their body would require for years and even decades.

Without breathing to get in the way, the seventh floor was far more comfortable and also in remarkably good condition in comparison to the first six. There was a lot less damage, such that it looked more like a person’s apartment that had been ransacked looking for valuables rather than the apocalyptic ruin he’d seen above. The fungus and creatures were also quite large, but they were far more uncommon. Only a few of them inhabited this place, and he subdued all of them, sending the dozen into the Inner World for study.

Since this floor was in so much better shape he did a more detailed search and found the answer to a question he had. How were the bigger bugs descending the floors when the staircase was blocked? They couldn’t fit in the vents, but it turns out there were other staircases spread out around the floor, but they only serviced the bottom four floors. An answer that led him to what appeared to be the final floor of the place.

This last floor had a sort of stone airlock. When he descended the stairs he stepped onto an array that flared to life. When it did, a stone wall slid into place behind him. Then he felt the pressure increasing rapidly to a point where he felt his flesh being compressed and his eyes watering. Then, the wall in front of him slid away and he stepped out onto the eighth floor.