Once again, another type of mana discovered meant another round of experiments getting summoned on Lan's schedule. But as time went by, he had a rudimentary 'checklist' established when researching a new type of mana, which sped up the whole thing.

Part of it was like this:

1. Test how a filled Mana Crystal influences the surroundings.

2. What does increasing ambient mana of such a type do to a chamber?

3. Determine what is the variable responsible for the quantity of mana present.

And so on and so forth. At this point, the whole thing was closer to a routine, but it nevertheless remained interesting to do. So, the experiments commenced.

An Air Crystal would be more aptly named Wind Crystal, as when it became filled with transparent mana, although it provided close to no illumination, the surrounding air currents were intensified, turning a passing breeze into a clearly-felt wind. When Lan looked for a cause of such a phenomenon, he found out that a concentration of Air Mana agitates other Air Mana in the surroundings, inducing movement.

'It kind of makes sense, with its nature and all. This type of mana likes freedom, and 'confining' it like this must be unnatural, leading to such a result.'

Though Lan didn't really know how he could use Wind Crystals for now, he guessed that harnessing such a reaction could be useful in the future.

Then, after carving out a small testing chamber, he filled it with Air Mana. Thanks to filling his Mental Mana with the right intent, and transmuting it into Air Mana, the process was gradual. At first, the chamber was completely sealed, possessing little air or oxygen, but along with Air Mana, both were increased all the way to a breathable level.

But as the concentration further increased in an enclosed environment, the nature of mana once again showed itself, with violent and rapid winds appearing out of nowhere, sweeping and cutting at the chamber's walls, as if trying to get out.

'So it seems that there is a certain critical point where oversaturation leads to such an outcome... I didn't encounter such issues before, but I better take it seriously. It would suck if a completed Floor gets cut into shreds due to a mistake.'

Then was the question of where exactly Air Mana came from. The answer was obvious enough: Air. It was nearly absent underground with no access to the surface, and vice versa being abundant above the ground.

But for the life of him, Lan couldn't figure out whether it was tied to oxygen in some way or not. When he tried to peer into molecular structure, his mana perception fizzled out, losing sense of any mana. It would seem he was not at a level to discover such secrets yet.

Putting off such a mystery for later, Lan instead decided to focus on interactions with other types of mana, hoping that the answer lay there. Obviously the first was Heat and Air Mana, with the well-known need of a fire for oxygen. In one of the empty chambers of the Fourth Floor, where there was some vegetation present, having closed it off, he increased the concentration of Heat Mana.

The greenery lost its life and dried up, some bushes being set ablaze due to the sheer temperature present in the chamber. But with it being enclosed, oxygen was being burnt out, causing the fire to wane as well.

At that moment, Lan started to conjure Air Mana into it, and voila. The fire began to burn yet again, as with Air Mana, oxygen somehow appeared as well. Lan was no chemist, physicist, or whatever else scientist was proficient in this, but even he thought that summoning things out of sheer will was not really scientific.

Nevertheless, the experiment could be said to be a success, with the flames burning brightly yet again. And as the concentration of Air Mana increased, they were ever brighter... Until they ran out of dry fuel. The following violent winds that were summoned extinguished whatever remained after.

Lan unsealed that chamber for recovery and cataloged his findings within his mind. They were... Intriguing to say the least.

'...I'll leave the hard stuff for later, I have yet to test other types of mana!'

The second test was Earth Mana and Air Mana. No apparent reaction except for usual interactions between the soil and the winds. If one could call blades of wind tearing apart stone in their fury a 'normal interaction', other things like wind erosion and kicking up dust were also present.

Air Mana and Light/Shadow Mana: No apparent reactions. Or they were weak to the point of not being seen. Lan heard something like wind shifting photons slightly back on the internet, but he didn't really witness such a thing.

Air Mana and Life Mana. Although Lan didn't expect anything to come from this, it would seem that Air Mana dispersed Life Mana in the surroundings like some kind of smoke or powder. It decreased the local concentration of it, instead spreading it over longer distances, carrying Life Mana along with its movement.

Lan wasn't really sure what to make of this, not being sure of possible uses either. But considering that when ultra-concentrated, Life Mana could fulfill the role of a potent aphrodisiac, this might as well be a good thing in some scenarios. Dispersing Life Mana on the surface could also promote the growth of life over larger areas, a useful option as well.

And finally, Air Mana plus Water Mana. Lan would be lying if he said that he didn't have any hopes for this one. He wasn't sure why, perhaps one could call it an instinct. And it would seem that his instinct was sharp.

Once the two types of Mana combined, a dense mist started to appear in the area of the experiment. Air Mana seemed to be weighed down by Water Mana, before mixing together. This combination resulted in mist forming, and with the increase in concentration, it soon turned to fog, which grew ever denser.

Lan realized that this was no interaction, but instead a full-on combination of two types of mana forming a new one.

'Mist Mana!'

The reason he figured this was because the 'feeling' of mana got mixed up. The playfulness and freedom of Water and Air turned to the gloominess and lethargy of Mist. Lan wasn't sure how two distinctly positive traits made a 180, but the result was before his eyes.

'Maybe it's something like overabundance turns to poison? Like too much medicine is poison, that same principle? Argh! I don't know! Air and Water make Mist, case closed! I can always research it later. It's not like I am capable of forgetting anyway.'

But the combination of two types of these two types of mana helped him understand the new type of mana too. Maybe because he could already feel those two elements from the start, he was partially attuned to Mist Mana from the start, requiring only some further focusing in order to fully control it and be able to summon it from scratch.

'Mist mana.'

'It is heavy and brings gloom.'

'And yet it can also herald the coming dawn or bring the air of mystery to the shores.'

'For within this mist and fog, endless mysteries take hold.'

If the moment when Lan attuned to Air Mana was a shout at the top of his lungs, then this time was the barest of whispers. No Beast or human heard it, not even the mightiest of the two species.

Instead, this whisper seemed to get trapped among the many leaves and branches of Lan's domain, the whirling of leaves echoing it amongst themselves again and again. Every tree seemed to take on an air of mystery for a moment, and a mist covered the forest on the surface, being densest under the Great Tree. The morning of that day was filled with mystique for humans.

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Lan, as always, paid no heed to the effects his actions held on the outside world, instead various theories were whirling in his mind.

'Why is the resonance fainter than before? Is it because Mist Mana is a combination instead of a completely new element? Or is it because I was mostly attuned already?'

Lan concluded that both were probably true. And after that, he realized that he had unintentionally made a giant leap to adding 'gates' to his boss rooms.

'Can I do it?..'

Lan reviewed the new element and concluded.

'I probably can! It may take some testing, but it seems feasible!'

Lan's attention surged towards the corridor between the First Floor and the boss' room, his 'fingers' were itching for action. He proudly declared the project name he was about to start.

'Project 'Fog Gates', totally not copied from 'Elden Souls', begin!'

During his conundrum of thinking of what way to create a door limiting the number of people, Lan thought of a mechanic implemented in one of the games he played in his human life. It was notorious for its difficulty, and there, the boss arena had gates made of fog through which the players had to walk through.

The thing was, they were one-way, and the player couldn't leave through them without defeating the Boss. Lan figured that if he fiddled with them somehow, then he could make only a certain amount of people pass through for the battle.

First of all, Lan decided to create Mist Crystals. At the same time, he lamented the fact that he was just testing Air Mana, and here he was fiddling with yet another new mana already, like some harem protagonist finding a new girl each arc.

'Still! The fog gates must be done! They will change the Dungeon forever!'

Exaggerating things a bit, Lan continued on. The resulting crystals looked as if there was dense fog swirling within them, and said mist continuously seeped out of them, filling the corridor they were created in. But, just as mist would, it continued to flow even past the confines of it.

'Well... I don't know what I should have expected, but that was unplanned for.'

In Lan's vision mist should completely fill out the corridor, flowing down from the ceiling like a waterfall, forming a wall impossible to peer through. Mist obviously wouldn't behave like that. Something else was needed to stop it, obviously.

Thankfully Lan was already on the move in search of a solution.

'Alright, how about Air Mana!'

A wall of wind seemed like an obvious solution... Until he realized it wouldn't stay in place either. It wouldn't remain stationary like some kind of ventilator.

'Earth Mana? I will at most make a door with that, and I don't need doors...'

But as he was contemplating how to hold back Mist Mana, he noticed out of the corner of his perception how the Mist... Was stopping at the edge he didn't want it to go past. As his focus was broken, it continued to flow as it was along the floor. But Lan, who cycled through possible causes of such a phenomenon, already had the answer.

'The one and only, my deus ex machina... Mental Mana! It channels my intent to mana, and Mist Mana is no exception! That means...'

He excitedly thought about the ramifications of this breakthrough, and his mood died down a bit because no matter how much he thought, he ended up with the same outcome.

'Do I need to continuously devote a part of my attention to keep it up?'

As he thought further, Lan also understood that it wouldn't pose that much of a problem, as his thought channels could already supervise each Floor individually, so adding a passive task wouldn't add that much of a load to split parts of his mind that were lazing around for most of the time.

Even now, when researching this project, only the thought channel responsible for the First Floor was active, and when thinking particularly hard, such as when he was attuning to Mist Mana, only then did Lan pull additional help, usually in the form of the thought channel from the surface, which was the most idle of them all.

Even so, as someone who lived in the twenty-first century, he couldn't help but long for the automation of the process. Maybe it was in his nature to take off workload when possible. But for now, he didn't see any further solution.

'Well... You know what they say, laziness brings innovation!.. I'll do the innovation part later.'

Staying true to himself, Lan continued with his current work. With Mental Mana being supplied together with his intent, the Mist did not leave the boundaries of the corridor between the Floor and the Boss Room. Gradually the mist seeping out from the single Mist Crystal embedded into the ceiling started pooling up and filling the corridor.

Soon enough, it turned from near-invisible, to 'I can't see shit', to 'Whatever beyond it is invisible.' Mist turned to fog, which was denser than smoke. It pooled inside the corridor, obscuring whatever lay beyond it. Lan was a bit unsatisfied though.

'Hmm...'

As he wondered what was wrong, it struck him.

'Not thick enough. And a bit too dispersed...'

A single Mist Crystal did fill up the corridor gradually, but it was a rather slow process, causing some of the Mist to disperse despite not seeping out of its confines. And what was the answer?

'As one wise man said: Use Mana. And if Mana doesn't work, use more Mana. Or something along those lines, I don't remember those days that well.'

Multiple new Mist Crystals were then made inside of the ceiling soon after. This caused the fog to thicken even more, filling out every single corner it could get to. And voila! A wall of rolling fog now stood as an obstacle.

'Now that looks mighty fine! But that's just part one! If I don't add any restriction against numbers, then this would end up just a visual trick adding a dramatic effect and nothing more. And that wouldn't do, now would it?'

Lan was also thinking of how to make an anti-escape feature. It wasn't that he wanted humans to die, but his bosses always fought to their deaths (though they would be revived), and he also didn't want humans to get used to rushing in unprepared. A boss is an absolute challenge of the Floor, and if you aren't sure you are ready, you shouldn't even think of challenging it.

'Who do they think I am? Someone whose bosses serve as harmless loot dispensers? Glorified pinatas? Hmph!'

The question was, as always, 'How?'

And Lan was always eager to find out. First, he tried increasing the quantity of Mist Mana even further. And sure, the fog was as dense as ever, but no significant effect occurred.

But as he looked at it being all gaseous, his old knowledge from primary school kicked in.

'Gasses. Liquids. Solids. It is all a question of density. Gasses could be liquefied under pressure, and liquids could be solidified under the right conditions too...'

Various things like high temperatures, pressurized environments, and needed reactions appeared in his thoughts occasionally. But he shook his nonexistent head and widened his nonexistent smile.

'But I have magic over here... And if I want to compress it hard enough...'

Lan sectioned off a part of the mist on the edge of the corridor and willed it to compress. In his mind, he held an image of a cube being squeezed tight, some gas within turning into liquid. As he did so, the fog converged further in that particular zone, before droplets of misty liquid started to drip from the ceiling.

Those few droplets turned into a drizzle, which then turned into something like a shower. At this point, Lan got the hang of the process and was also witnessing such a spectacle while continuing the compression. Seeing that the Mist Mana was running out, he let in some more while not letting the condensate disperse.

Soon enough, that shower turned into a curtain of water, which grew ever thicker. Once the liquid hit the ground, it dispersed into a gaseous state, before being gathered back together into liquid. But Lan noticed that it was no liquid he knew of.

'It isn't water like one would expect... It's the color of the mist... As much on the nose as It might be, it's literally liquid mist. Mist Mana turned to liquid!'

While he observed it, he noticed that the feelings emanated from it were far more pronounced as well, gloom and lethargy practically radiating off of it. He couldn't help but wonder what kind of effect it might have on living beings.

As if ordained by fate, a rodent was passing by with the goal of descending to the Second Floor. It was a bit confused by the mist, stumbling about for quite some time, though the distance wasn't that large. Once it went closer to the liquid, its movements slowed, and once it touched it, it directly fell on its side.

Lan thought it died for some reason, but he noticed it was still alive, just looking as if it lost all will to live. After a few seconds of thought, the answer clicked.

'Lethargic... So that's how it is! One of the aspects of mana directly influenced it! I do wonder if it is the same for larger creatures with greater will!'

But there was no conveniently large predator passing by, and Lan didn't want to experiment on Tag and Nacht, they had already died for him multiple times, and they deserved their resting times. So, while keeping an eye out, he was also thinking about the number limiter.

'Something to let in some but not the others... I can control the entire corridor somewhat... So I need to expel them... Expel? Maybe that's the solution?'

Lan didn't know how to set up some Thousand Illusion Bewildering Grand Ancestral Formation, but he knew that he had Air Mana. Compressing Air Mana could generate violent air bursts. He could control it using Mental Mana to some extent. Air Mana was part of Mist Mana. Conclusion: Could he blast away people using it?

'This calls for an experiment!'

Lan already knew that Water and Air made up Mist, but he wasn't sure how to go about the separation of the two. But if Mana was present, it could be used. Lan focused intensely, focusing on the mist. Thanks to how dense it was, it didn't take much.

Looking past the mixed layers of gloom, he tried to see the part longing for freedom and separate it. But he didn't see it, Mist, true to its name, concealing the secrets within.

'Then maybe...'

He tried to focus on the feeling instead of 'vision' he sent out the intent of 'freedom', waiting for a response. And he got one. He sensed that part that was ever-moving, the opposite of inaction.

And, he grabbed a chunk of it and pressed it together. As expected, a violent gust was held within his 'grasp'. All that remained was to give it direction.

And with his intent, he gave it one. Away from the boss room. He may have underestimated the impact a bit, causing him to involuntarily think.

'Is it too late to say 'Fus Ro Dah'?'