I mean, we kinda know how the other features of the same kind work.

Resistances and Invulns are passive bonuses.

Magic uses MP.

Martial Arts take toll on the body, so that's quantifiably Stamina.

What exactly does a Skill use?

Time cooldown? The only clue I have is the comparison with Super-Tier Magic, which is described as to be more akin to a skill – which I believe is really referring to the fact that it doesn't use MP. If we extend the connection, then we have the cooldown.

So that's it? It's not really a matter of division, but the Skill actually being the root for Magic and Martial Arts, both of which essentially being Skills with extra cost?

Edit – I just remembered that regular Magic and Martial Arts (as far as I know) do not have time limits, so I guess that narrows down to time cooldown after all. So... that's it then? Time cooldown? Does that mean I can spam Magic and Martial Arts, but not Skills?

If you want to get technical... we can break down the thermodynamics of various abilities. But I think the answer is that it's just a vestigial mechanical feature of game design. A person has done XXXX or put a certain amount of time in and learned certain abilities.

Magic itself is fueled by Mana. Wild Magic is fueled by the soul, something distinct from Mana. Martial Arts draw on... something that leads to fatigue or physical strain. But what of skills you say?

Put simply, the most likely candidate is the Class themselves. It may seem odd, but a Class Level is like a Living Enchantment of sorts.

As for Level Up (growth [seichou]) it’s a kind of evolution [shinka] of the species which comes from Maruyama’s way of thinking. Even if the same edged instrument is used to stab, the degree of the wound would differ between a bear and human no? That’s the sort of impression [at play here]. The reason high level humans have a high resist rate to poison and illness is for a similar reason. That is to say Level Up (Growth [seichou]), please perceive it as the evolution [shinka] into a superior living [joui no ikimono] thing. It’s the 􀏐irst step to becoming an ubermensch [choujin].

Ah, one can also train[tanren] their body[nikutai] in addition to this. This may seem like a game explanation yet, there is foundational physical strength [su no kinryoku] (which can be trained) + Level Up Physical Strength (evolution [shinka]) + and various corrections from classes etc (power that comes from unfathomable magical power [maryoku tekina fukashigi no ryoku]) should be the plan

[V5+6AT]

Basically in our world, we don't have Levels per se. We have people equivalent to certain levels yes, but we don't have the feature of certain stronger people being able to tank cyanide or something like Mustard Gas. Levels are a magical force, typically handwaved by most. Typically, Physique, the act of strengthening yoru body by getting jacked and ripped is the limits of getting stronger on Earth. And not all people have the same potential for this (Climb laments his own lacking physique).

Notice how Maruyama segregates Levels from Class features. Levels give flat features. Theoretically, a creature could evolve and just have more levels but have no classes. These flat features are things like resisting effects from weaker beings, resisting poisons or diseases, or having stronger children, or scaling down enemy damage.

"...How surprising. Are you at your wits’ end because you are all weaklings? This is truly a country of idiots. All the children that I sired turned out to be nothing but useless." People born in wartime were stronger than those born in peace. That being the case, warfare was an opportunity to awaken the power latent in all living things. However, he had not heard about anyone whose power had awakened so far. Still, he should not hold the people solely to blame. His many children had turned out that way as well. Their true number meant nothing to him so he paid it no heed; why would anyone bother counting pieces of garbage? It was probably because their mothers’ blood was too strong. None of the offspring he had bred from them possessed even a fraction of his power. The children born of weaklings would only be weak. Thus, he needed strong mothers. That was why he had sent the women to the frontlines during the Theocracy’s invasion. This war might have allowed those weaklings to grow.

[V11]

Perhaps it was a weapon carried by the Pleiades, Ainz’s immunity would have been defeated thanks to the massive amount of data within them. The best example of that was CZ and Yuri’s attacks from just now. However, certain skills were calculated based on the user’s level. Entoma was a prime example, since she possessed many of these user level-based attacks. Entoma was only around level 50, so her attacks did not bother Ainz at all. In addition, if all damage from an attack was nullified, none of the rider effects would take place either.

[V13]

Cure Elim-kun is actually more powerful than his 95 levels imply. Of course, thanks to level-based damage adjustment, his odds of victory are lower.

[V14]

Someone having just Normal classes like Farmer are pretty much like this. But Classes are specialized forms of Evolution that grant access to magic, Martial Arts, or even minor feats. Like you surmised, Skills do have limited uses, either daily or with cool downs. Ziggy just prefers to go with the idea its a Living Enchantment of sorts, since it resembles daily use limited items or monster abilities.

It's sort of how people talk shit about Monster Levels, like Hamuske or Dragons. They don't really learn a whole lot of skills or abilities. But they do get slightly stronger overtime. That's actually pretty normal really, it's weirder that someone can level up and learn all sorts of feats to defy or alter reality don't you think? Every creatures anatomy sort of informs what's it good at, where it can live etc. Isn't it odd people can train themself to excel at harnessing mystical forces they were not born with to any great extent compared to a dragon's breath growing stronger with age?

One could train to be a warrior, a magic caster, or a thief. It was not just humans who could train themselves in such techniques. While creatures with racial advantages generally were not inclined towards such training, some of them would put in the effort to pick up such skills, and that made them very difficult opponents.

[V12]

People also shit talk the Wild Magic ring for this same reason. IT just gives additional levels. That's it, there's no indication that it gives you new Martial Arts or new skills. But it does let give you a stronger body for damage mitigation, the stats associated with a Level up, and even a greater capacity for Martial Arts themself. The power source for skills seems to be whatever it is you feel when you use that ring in my eyes. IT's that warmth. That POWER.

Gazef activated his trump card. Heat bloomed from his hands, and spread to envelop his entire body. Gazef broke the limits of his physical body and stepped into the realm of heroes.

[V1]

It's true Super Tier spells don't use MP but... there's suggestions that it's using something. Just not what Skills use if others can perceive it. Skills are a very internal thing. They are quite literally the manifestation of one's very own efforts in life, their struggles to survive made manifest. I think the most obvious examples of these are Paladins and Vijar. Vijar in particular pretty much the embodiment of a Honor fighter, one who fights for prestige like the combat Samurai or Knights who aimed for well known figures at tournaments or in back alley duels. I shank anyone that tries to argue Showdown Declarion is a Martial Art when we have never seen a MA that affected enemies into aciton like this and the fact I'm pretty sure Vijar's class had this as a Skill.

Only a knight who physically expressed the justice they believed in could be called a paladin. Therefore, although he did not say it — largely because his wife was very scary — to him, paladins were essentially zealots. ... Remedios activated a skill from one of her job classes, Evil Slayer. The divine power within her holy sword intensified. ... She activated a skill, and then her martial arts, using her holy sword to strike a blow with all her might.

[V12]

"–Human. Do I not have a title like that?" "I’ve never heard of the name Vijar Lajandala. However, there’s an axe-wielding Zoastia like you who’s quite famous. It’s the Demon Claw, Demon Claw, Vaju Sandiknara." "That was my old man" Vijar snorted. "I’m the heir to the title of Demon Claw, Vijar Lajandala. I’ll make sure you think of my name when you hear the words Demon Claw." ... "You’re insulting me by taking your eyes off me!" Vijar swung furiously at Remedios. ... Vijar growled. He was not wary of a worthy foe, but delighted. "Hey, fledgling. We’re done here, but you’ve been at it a long time. How about it, need help?" "You must be kidding. My legend will be tainted if I need your help to kill her. Many people will speak of this if I beat her in a one-on-one." ... Vijar laughed as he watched Remedios break into a run. It would seem he had misunderstood something. "Ho. It seems you’ve made up your mind. That’s the way! Fight me with all you have! Give me a battle worthy of a legend! [Showdown Declaration]!"

[V13]

Basically, New World beings are sort of the ultimate role players. Neia proved to us you can't just get a class because you work for it. You actually need to satisfy the flavor text or ideal of the class. It's why Jircniv is such a great Emperor, he was born suited for it, and he's acquired job classes by embodying that natural affinity.

To me this is one of the natural magics of this world. IT's related to flavor text shit becoming real. Rather than just doing X to get Class Y, you have to be X to get Class Y. It's why you get Normal classes by working hard at something mundane outside combat. It's why you can train outside killing shit and still level up. IT's why peopel who attend the Magic Academies can level up a whole Tier by just going to school. Martial Arts resemble Skills because they seem like a sub system of this magic. People can create unqiue Martial Arts because they work hard to accomplish a dream of striking the fastest or transcending their limits. The main difference is just as level are limited by Level Cap, Martial Arts themself are limited by Warrior Levels (Eruya was noted to have learned Greater Ability Boost earlier than he should have or Fortress was noted to be a veteran only Martial Art by Neia). The key difference here is that Levels, or more specificialy Job Classes for New Worlders can complete ignore the level requirements they should have had in YGGDRASIL, see Ninja and Cursed Knight.

I suspect the Pearl of Death willingly submitting to Ainz is a sign of this power in action. Ainz is an Overlord, a ruler of death, so wouldn't undead see Ainz how humans see Jircniv as a natural ruler? Related to this, Renner being a Princess but faking what a Princess should be and getting Actor levels instead seems to suggest that you can't just fake your way to a class. Neia can't pretend she knwos Justice and get Paladin right? This is also why Ziggy thinks Genius classes are actually notated on character sheets, they didn't just work hard, these people are so suited for their class they actually bypass the limits of the Level system and get mini perks sort of like Normal classes, like learning a few extra spells or learning shit earlier than normal.

Thus, I can't agree with you that Skills are the root of Martial Arts or Magic. It's true all three are related to Levels, there's a bodily constrain in overusing either of Martial Arts or Magic. In contrast, Skill overuse doesn't appear to have any fatigue to speak of. There's another power at work here distinct from just number crunching. IT's a weird Magical Roleplayinig Force. Perhaps it has somethign to do with how New Worlders see dying and coming back as losing life force, what shoudl jsut be levels, but we see a Wild Magic user turn undead and lose their natural ability to replenish their Wild Magic 'mana'. There are levels and then something that comes from Levels, that comes from being alive and growing, or being unalive and growing. Soulbreaker breath does not discriminate between the living and undead...

At this point I'm just rambling though.

What benefits Adventures have if they join the Sorcerer Kingdom?

The Ultimate Dream - Now Within Reach

Usually, the stronger the nation, the less respect and work Adventurers get. So people dream of the good points of adventurering but the majority of your work is killing shit the military can't, IE scary ass monsters. Sure you get paid well, but most of you die or drop out before you're fully trained. It doesn't help the guilds favor and try to nurture the talented people. If you look at the attrition rates, despite there being rankings to protect them from danger, the death and drop out rates are really high, 65% of commoners die within the first year, that's nearly 3 out 4 people who try to make a go of it starting without relevant experience just die. Even if you do end up one of the lucky ones, you're treated no better than expensive exterminators. Even if you try to get into less dangerous or dirty work, you have to deal with the dangers of the underworld. Despite all that, if you stick it out, you may still end up drafted by the nation in big disturbances by force as the frontline meat shields, so you might have well have become a solider.

All of those realities got thrown away if you join the Sorcerer Kingdom. Ainz already has an army far stronger than any Adventurer party. He already deals with the mundane monster elimination. He has mandatory training. And most of all, he actually wants you just for the part of the job you dreamed about, exploring and experiencing new things.

"Still …the life of an adventurer is pretty banal." Adventurers. Once, Ainz dreamed about that profession. He envisioned them as people who chased after the unknown and had adventures in various parts of the world. Ainz had previously thought that adventurers were a physical manifestation of the right way to play YGGDRASIL, but after listening to the Guild receptionist, he realised that adventuring was a more realistic and more boring job than he had expected. Simply put, adventurers were "anti-monster mercenaries." Although some parts of it fit his dreams of them for instance, delving into the ruins of kingdoms destroyed by the Demon Gods two hundred years ago and investigating mysteries in uncharted lands for the most part, they were simply monster hunters. Every monster possessed different special abilities, so they could only be taken care of by people who knew more tricks than average soldiers. Just going by that point, one might think that they were heroes who were loved and relied on by the common man, like in games. However, the reality was somewhat different from that. This was because the ruling authorities did not smile on the existence of armed groups which they could not control. Therefore, aside from the prices they commanded, adventurers did not have much status. Another reason why adventurers were not accepted on a national scale was because of the same thinking which made companies look for cheap, local temps than employing expensive permanent staff. Thus, much like how temps were treated by companies who could get by without hiring them, adventurers were held in lower regard in those nations which could eliminate monsters by dint of their own military power. According to the Guild receptionist, there were no adventurers in the Slaine Theocracy, while life had gotten worse for adventurers in the Baharuth Empire after the ascension of their new Emperor. Ainz banished his mild disappointment from his heart. It was a common thing in life to find that a job which one admired was hardly as glamorous in reality.

[V2]

The new vision of adventurers of which he had spoken was a shining and glorious one. In the past, there had been adventurers who had set foot upon unknown lands. However, most of them died far from their homes, or had broken down in the face of reality. Only a handful of people could actually do such a dangerous thing. But now, the Sorcerer King — a magic caster who wielded absolute power — was offering his full support to them. That opened up a whole new vista of possibilities to them. Contained within that was the possibility of becoming true Adventurers.

[V10]

"...Therefore, I intend to incorporate the Adventurer’s Guild into my nation. There are those who fear that they will lose their freedom and be shackled down once the Adventurer’s Guild becomes a national organization. I cannot completely rule that out. However, like I have just shown, my strength is more than adequate. I do not intend to use you as tools for war. The Sorcerous Kingdom thirsts for those who truly seek adventure! All you who wish to explore the unknown, who wish to understand the world and thus dream of becoming adventurers, come to me!"

[V10]

"—The Adventurer’s Guild? Could it be he wants to do something to the Adventurer’s Guild, which is why he opposed the vassalage?" "What about that declaration?...Would permitting it be a good idea, Your Majesty? In a few years’ time, a lot of the best and brightest of the Empire might end up flowing out of the country." "...I did not get that at all. Tell me how you arrived at that." "While doing as he says means that one’s freedom might be restricted, having the incredibly powerful Sorcerer King as backing is a very attractive proposition. In the adventuring profession, far more people die than manage to make a name for themselves. However, with someone that powerful supporting them …well, at least that’s what those people with no confidence in themselves will think. Also, since we have knights, there aren’t many jobs for low-ranked adventurers in the first place." "An outflow of talent …Although they may not have faith in themselves, it doesn’t mean they’re not capable." There were people who were talented, yet lacked self-confidence. Yet, it would take a very confident person to explore a new world.

[V10]

"...Well, we can conscript high ranking adventurers, the kind who are used to defeating monsters and the like, as part of mobilizing our people. If we muster up our full fighting power, Jaldabaoth’s hardly an unbeatable foe. The fact is, he’s already been defeated once before." The Adventurer’s Guild had strongly protested the conscription of adventurers into the army, but Calca had not revoked her order. It was only to be expected — this was a matter of national importance, and splitting their strength was foolish in the extreme. In addition, the Adventurer’s Guild was hardly as powerful as the Holy Kingdom itself, so forcing them to obey was a simple task.

[V12]

Adventuring was a profession which was very much at-your-own-risk. While it seemed that Momon fully understood the situation, there were a lot of mis-informed fools out there. There were those who believed the guild would provide training. Certainly you could 􀏐ind schools for that sort of thing and if you could pay, instructors were always available. But nothing is ever free. The Guild will never entrust newbies with important assignments and that certainly helped to keep the attrition rate down. In any case, the Guild was not big on wasting resources to develop newbies. The Guild preferred to save that for the wheat that appears from the chaff. Basically adventurers who had just registered like Momon go through a large sieve.

[WN]

"There are people who take up requests involving fighting monsters in order to gain experience, but I think that's not a very good idea" Ishpen suddenly stopped. "I'm not trying to scare you but for ex-normal villagers who take up the combat assignments, 50% die as novices, 25% quit and 15% of the remainder die within a year." "Is the chance of dying during a promotion test high?" "There are cases. Out of the 50%, 30% are so. The rest take on monster requests beyond their abilities, or are sometimes assaulted alone by monsters." From what Ishpen gleaned from adventurers, in a life-or-death struggle with monsters, village hicks who rely on brute strength don't have a great survival rate. Something else is needed, something that most villagers lack.

[WN]

National Support - But No National Poaching Pressure

Ainz alludes to this, but by being affiliated with Ainz, the True Adventureres have the backing to prevent being attacked or held hostages or eaten by other nations due to their link to the Army Destroying, Hero Besting Sorcerer King who will eventually have a monopoly on Physical labor. Effectively, Adventurers will get to go to any nation like how they can freely go through the human nations.

The main difference with Ainz and other nations is that unlike strong nations, who pretty much start to consume their guilds for their own militarizes or are forced into action like the Holy Kingdom, Ainz has proven that he doesn't need to pressure Adventureres to supplement his military.

"...The details of this sort of thing are top secret as they are linked to national policy, so I cannot discuss this openly. If invasion and conquest would be advantageous to the Sorcerous Kingdom, we might end up doing so, or if they would only beget disadvantages, we would avoid such acts. This is quite common among countries, am I correct? However, if it comes to the simple matter of invasions, I can plainly state that I have adequate military forces at my disposal. I do not expect adventurers to collect information on enemy nations, nor do I need them to scout routes for me. As I said earlier, I simply desire them to explore the unknown and discover all sorts of things. I give you my word on this."

[V10]

I will help you stand on your own, with the aid of power you cannot imagine.

[V10]

Training and Practical Experience

Avoiding the high death rates is most obvious when you consider that Aizn will have his adventurers able to not only practice exploring but also combat in a controlled environment of his undead. This allows people to not only improve safely, but even lets them try out team combinations and do trial runs. That's something no other Adventurer Guild can offer.

All that was left was the most important part; the inducements which would make more adventurers want to join the Adventurer’s Guild of the Sorcerous Kingdom. "The support which the Sorcerous Kingdom offers will primarily include the establishment of a training facility. It would be a terrible loss to blaze a trail into distant lands, only to be slain by unknown monsters. Therefore, a more practical training method than the current model — that of live combat against monsters — will be required. Considering that adventurers need to get used to team combat, it might be a good idea to build a labyrinth for them to delve into." And the part of the monsters would be filled by Nazarick’s POP undead. "I feel that this is a very good idea. Only, it would surely be a sizeable under- taking." Since the staff would be composed of the undead, who did not require salaries, the operating costs would not be too high. However, there was no need to be completely open with the information. One ought to sell favors without hesitation when the need arose. "Indeed, this would require a sizable initial investment. However, that is within the allowable limit for necessary expenses. After all, adventurers are a valuable human resource for the Sorcerous Kingdom."

[V10]

Affordable Equipment - Runecraft Monopoly and Exotic Equipment

Foremost, Ainz and the Dwarves have a very self feeding relationship of Ainz gives them labor to produce ores and equipment and he buys them for his nation at lower prices. This means Adventurers can get access to Dwarven craftsmenship without paying out the ass or travelling to dangerous places.

Access to high quality magic items (failed Fluder inventions of no strategic value) and weapons made with 'enchantments'. Due to their low production cost, these items will always be affordable and readily available, even if just rented. Effectively, any Adventurer team can get the same great quality items for their level like Climb did without having to be favored by the royalty and top adventurers of their nation.

"Also, I was born in this city, so I know many people here. And also, all sorts of magic items flow through here." "Hoh, magic items, you say." "Yes. After all, magic items have saved my life in the past, so as an adventurer, I would naturally want to base myself in a place with good access to them." In YGGDRASIL, there were also stories of how a simple magic item averted a total party kill. That said, he had also seen many people who looked like adventurers in the Imperial Capital’s markets. In other words, if he could set up a larger-scale magic item business than the Imperial Capital, it would be sure to draw adventurers over. He would probably be able to achieve excellent results by making magic items with appropriate data crystals and then auctioning them off. However, that would fundamentally be raiding Nazarick’s reserves, and there was no guarantee that Ainz and the others would not find the technologies developed with those items as a base pointed at their throats instead.

[V10]

"...Then, Fluder. I wish to have you participate in the magical research of the Sorcerous Kingdom. However, your spells will not be put into circulation. They will only be shared with me and those whom I trust. Can you bear it? Can you forsake your desire for fame?" "There will be no problem at all. The only thing I desire is to glimpse the secrets of magic. I desire nothing else."

[V10]

"—I see,the Merchant’s Guildmaster smiled. So that’s why you suggested undead labor. If we could excavate minerals in large quantities, then there would be an ample surplus. In other words, you want to keep the price of ores low. Is that it?" Ainz had not thought that far ahead, but Ainz nodded and pretended that it was the case. "Indeed it is so. You have seen through me." No wonder, the Dwarves thought as understanding dawned on them. "Also, I would like the weapons and armor crafted by the forges of your nation. I hear that Dwarven battle equipment is of exemplary quality."

[V11]

All the people Ainz had asked about this topic agreed that this was an unassailable fact. However, processed weapons and armor were more expensive. If they bought from the Dwarves, then there would be fewer armorsmiths and weaponsmiths in the Sorcerous Kingdom. If there was a clear technological difference between the two countries, it would be better to improve the technology of one’s own nation rather than take the foolish action of buying large quantities of superior arms and armor. However, if there was no competition, the smiths within the Sorcerous Kingdom would not hone their skills. The weapons and armor purchased from the Dwarves might serve as a positive stimulus for that. Of course, there were many ways to handle this, such as by collecting tariffs and the like. One had to ensure that he could make a profit off the Dwarves and not constantly import from them, among other headaches. The simple answer would be to hand all this to Albedo and Demiurge. However, Ainz had his own considerations as well. His plan was to limit sales to the newly-founded Adventurer’s Guild, or rent them to adventurers. Low prices were very attractive to adventurers, and keeping them alive would also benefit the Sorcerous Kingdom. If they could sell old goods at low prices, they might be able to increase the survival rates of adventurers at the same time.

[V11]

Does that mean runes are part of it? Mm. Taking control of the Dwarves …Not bad. The Head Librarian and Demiurge are conducting experiments with scrolls. Nfirea is working on potions. Fluder is handling magic items. Then I shall let the dwarves take charge of weapons manufacture. All sorts of experiments to strengthen Nazarick were taking place concurrently. Ainz smiled in satisfaction as he thought about them.

[V11]

"Alright: my words are a very simple proposal, as well as a request. Come to my country. I want to use your runecraft to begin a revolution in magic item enchantment."

[V11]

Resurrection Insurance

State sanctioned resurrection gives you peace of mind. You might lose lifeforce, but you basically get a CONTINUE in life while also doing the dream job you wanted.

"Personally, I would feel safer if I could count on resurrection magic. With that, we wouldn’t have to mourn the loss of talented young men. Although, I’ve heard that resurrection magic drains life energy, and ordinary people will be reduced to ash if one tries to resurrect them. Is that true?"

[V9]

"The Martial Lord is dead! Who will verify his death?" There was no answer. "Death is the end of everything. Yet — as some here might know, death can be fought off." Ainz withdrew a wand, and pointed it at the Martial Lord’s chest. ... "Resurrection magic is the province of high-level priests. However, it is not a challenge for me! That said, the appropriate payment in gold must still be made! I, who have conquered death, shall back you up! Come to my nation, you who seek to become true adventurers!"

[V10]

Exposure to new techniques