Arethar kept his word: long before the sun reached its zenith, the group had already covered all the necessary road and had arrived in front of what looked like a large pile of rocks. Haku, Rhaegal, Tikka and Teramon already knew it, since they had explored the desert around the Thul Oasis well, but they had never gotten very close to it because it had always seemed useless to them (their 'outings' outside the oasis were almost always due to the search for sand worms, which don't approach rocky areas). When they were close enough, Arethar uttered a few magic words, and the whole area seemed to shiver as if it were made of rubber, and then the rock pile changed shape revealing a great hollow about ten meters wide in the center of it which dropped far into depth and on which there were stairs that was clearly artificially constructed.
"Wow... what wonderful magic" Isaac murmured upon seeing that scene. His job was to observe and understand the spells of the arachne people, so obviously he had been very careful when Arethar had uttered the spell, and had been amazed by the complex fusion of the four elements of elemental magic; they weren't tied together, as humans, elves, beastmen and in general any unknown race used to do when they had to use two spells at the same time, but they were concatenating, like ropes that never touched but which formed circles with the which penetrated the circles of other magic. In short, a bit like the links of a chain, which were not linked together but worked together because each link was inserted into the others. That intricate structure demonstrated that the arachnes people must have had great magical knowledge... but at the same time it also seemed to demonstrate that they stopped at elemental magic, thus excluding the magic bestowed by the gods. Such a combination of elemental magics to hide the passage proved that the arachnes could not use light magic as well as its dark counterpart, dark magic; Isaac still didn't know if they knew life magic or death magic, but he thought that was unlikely. From personal experience he knew that every time a people obtained a magic of the gods, that people tended to use it for all the more complex jobs; as a result, such use of elemental magic was highly likely to mean the absence of any magic given by the gods. "Are you a mage?" he asked Arethar.
"A wizard" the arachne replied with a smile. "Among my people it is important that the prie... that those of my social class know many kinds of magic, since we use it for many things. Living underground, it is the fastest way to mine, to secure the tunnel, get materials..."
"Okay, I get it" Isaac stopped him. Clearly for a civilization that lived mostly underground mages must have had an advantage over warriors: even if it was possible to dig tunnels simply by fortifying the body, it was still much easier to use earth spells to open a passage in seconds. Also from what he understood the arachnes didn't usually have conflicts, and since they lived the underworld was divided into several caves it was probable that when they decided to settle in one of them they would clean it of all dangerous beasts, so they didn't need much of soldiers or hunters and therefore of warriors. Other than a few that could be used to explore or gather resources, warriors were unlikely to play a major role in their civilization, unlike mages who were probably used for just about everything. Isaac almost found himself smiling: it was incredible that an entire civilization had moved on a completely opposite path compared to the rest of the world due to the simple conditions of the environment where they lived. His academic interest was piqued by this realization. "Well... since you're also a mage, I'd like to talk to you about our respective knowledge. If you agree, I'd be very curious to find out something about the way you use magic, and I could talk to you of ours..."
He wasn't sure Arethar would accept, but luckily the arachne didn't seem against the idea. "I'd be happy to. After all, it's up to us mages to try to learn as much as possible about the magic that permeates this world, and it would be an affront to our role to avoid comparing our knowledge and potentially exploiting it to improve ourselves"
Isaac nodded. Obviously, that must have been the mentality of a civilization that had made magic its basis. Just as in the rest of the world it was common for warriors to challenge each other to a duel to test themselves and learn new techniques, in the civilization of the arachnes it must have been common for mages to talk to each other and observe each other's spells in order to increase their knowledge and with a little luck even putting them together and creating more powerful, faster or more efficient spells.
"Excuse me" Efren said suddenly stepping forward. "I know we haven't started negotiations yet, but... do you think that in the future it will be possible for us to use this passage freely, to go underground to meet your people or into uninhabited caves?"
"Yeah! It would be very useful for our progress. Obviously we will be happy to pay you" Atelas intervened giving him support. Obviously both were thinking the same thing: to use that passage to allow all adventurers to go underground and explore the caves. If the Arachnes had accepted, everything would have been easier and finally their new guild would have taken off. Obviously they weren't going to do it for free: they would pay the arachnes by paying a percentage of any resources they got. After all, the underworld could bring great wealth for everyone, so it would have been possible to please everyone. And even though the arachnes had lived down there for millennia, both Atelas and Efren doubted that they would refuse help in exploration or resource gathering or any other work that might be asked of them.
Arethar seemed to think about it for a moment, then he shrugged. "Well... I can't give you an answer because I can't make this decision by myself, it's not within my competence. You will have to wait to speak to the leaders of my people to find out whether they will accept or not. But I am sure that if you are convincing and you present a profitable deal, they will be happy to work with you in the long term. But again, don't take my words as a guarantee, it's just my personal opinion"
"Okay, we'll talk about it later. Now let's go" Haku said impatiently; he was already annoyed enough for that day and didn't feel like waiting for everyone's comfort. Arethar of course obeyed him immediately, as he continually did, and so led the way and the party began to descend the stairs, which were set parallel to the wall of the cavity and thus descended in the form of an almost circular spiral.
It was impossible to tell how deep the cave actually was: certainly more than a kilometer, perhaps even more than two. It was impossible to see the bottom: even if the sunlight penetrated from above, the further you went down the weaker and weaker it became. After just one hundred meters it already seemed to be dusk, while after three hundred it seemed to be at the moment when the sun had already disappeared beyond the horizon and was leaving behind only a slight light that was destined to disappear in a short time. Haku, Rhaegal, Tikka and Teramon had no problem moving even in such dim light, but for all the others it was necessary to use torches to avoid the risk of someone tripping and falling downstairs. As they descended it was also possible to hear the roar of the water, and soon several waterfalls began to fall into the hollow; the water emerged from tunnels adjacent to the stairs, near which the passage was replaced by a small bridge. "These allow access to the shallower caverns" Arethar explained. "Along this ladder are several outlets that allow you to enter the various layers of caves, from the smallest to the largest deep inside. My people use these huge cavities to move faster between caves as they open so many connections to all the underworld"
"So you didn't create these passage?" Misune asked.
"Oh, no, miss! We're good at digging, but not that good" Arethar replied with an amused grin. "These vertical cavities form spontaneously every few thousand years. We believe they are the results of thousands of years of earthquakes and water erosion weakening the rock until it collapses, and thus all the tunnels that were previously sealed by meters and meters of rock suddenly become accessible simply by using this passage. Most of these cavities are between one and three kilometers deep, and are the ones used most by my people... but sometimes they form closer to the surface and therefore they create an opening to the outside, like this one. In fact, this one is little used: although you see stairs, it is rare for my people to use this passage... most cities are under a kilometer and a half deep, hardly anyone ever comes up here except to collect some materials and resources that are closer to the surface"
"So all the adjoining caverns can be accessed from here..." Rhaegal said in a dreamy voice. His adventurous spirit was starting to resurface. "Efren, Atelas, did you hear? It could be much easier to explore the underground through this passage... we could be able to access deeper caverns, move faster, obtain resources... that would be wonderful!"
His two friends nodded vigorously. They could clearly see the potential of that cavity: through it, they could descend very deeply in a few tens of minutes, instead of having to look for very intricate and often dead-end tunnels. Convincing the arachnes to let them exploit that passage immediately became the main objective of the three: everything else no longer mattered to them, by now their adventurous nature had taken over.
The group continued to descend until they were more than two kilometers deep, where the cavity stopped: the ladder reached a flat area and all the waterfalls converged in a small lake from which a river started and then entered a tunnel. Arethar led them through this tunnel (which had a small area above the river that you could walk on) for about two hundred meters, until they came to an immense cavern even larger than any Rhaegal and Atelas remembered exploring, within which the river continued to create a large central lake. "Where should we go now?" Haku asked to the arachne.
Arethar pointed to the other side of the cave. "We'll have to continue in that direction for... well, quite some time, and we'll go from one cave to another through specially dug tunnels. After about two or three days' walking we'll reach another cave, which this time will be completely underground, through which we will descend again up to three kilometers deep. It will be there that we will find the passage to reach Tigu-chtu-tal"
Haku let out a soft grunt. He had imagined that the arachnes had their own paths designed to be able to travel quickly, but he had not imagined that they were so efficient. It had taken Rhaegal and his team two weeks to reach just 1.2 kilometers deep, while now Arethar claims he can take them to three kilometers in a few days. The civilization of the arachnes was very well versed in the underground if they could travel such distances in such a short time. "I understand, thank you. Please lead the way," he said to Arethar, gesturing for him to continue.
Arethar seemed over the moon to hear Haku say 'thank you' to him, as if the dragon had just promised him a bag full of diamonds. "Of course! Please, follow me: we still have a long way to go"