The power system of JotS in not a single thing, but a combination of many different varieties. This will get long as it's very deep.
Mana- mana is a natural energy that is present in the air, it's also called the 'essence of life' and all living beings have it.
All beings have a 𝐌𝐚𝐧𝐚 𝐂𝐨𝐫𝐞 which exists in their inner domain that allows them to absorb mana in the surroundings, convert the said mana into usable elemenal mana or usable pure mana and expel the usable mana in their inner domain to store it. (basically dantian if you've read enough xinxia, I'll use innate/inner domain in the main story..but a better word would be dantian because it better describes itself)
The holder can also send their consciousness inside...
The cores can be elemental or pure mana cores. They evolve as well- I'll brief on it down the line.
The domain expands as more and more mana is collected. It is like a bottle inside a bottle. Any mana used is passively returned to the body once used, however- inner domain can only be expanded when one is consciously trying to force it and this is the reason why focus and training is required. This increases total mana capacity.
(There's a limit to how much it can expand different for everyone)
The useable mana can be then used in various ways, it can be used to reinforce the user's body and physically enhance themselves for hand to hand combat- however, the most important use for it is to condense it, different results can be achieved depending on the mana core type-
If someone with just pure mana core condenses their mana, it'll become a hard body mass. They can manipulate the shape they want to condense to and create weapons of their choice
Pure mana cores are element-less cores.
𝐄𝐥𝐞𝐦𝐞𝐧𝐭𝐚𝐥 𝐂𝐨𝐫𝐞
Elemental cores are cores that convert the collected mana into elemental mana which is used to conjure the element it belongs to.
Elements are divided into four types types- natural, sub natural unique, supreme.
Some natural elements - fire, water, earth, wind,
Sub natural elements- metal, blood, lightning, wood, ice....etc.
Some unique elements - storm, forest, holy, shadow...etc.
Some supreme elements - light, space, death, life...etc.
To use the elements, a sorcerer pours out their mana out of the domain in the real world and condenses it, when condensed enough- they become the said element.
For ex- when a fire mage condenses some of his mana, it "sparks" into a fire.
The amount of 'element' produced is a lot less then the mount of mana spent, the loss of mana can be decreased as one trains enough.
Some people can use all their magic without any loss. Such people are countable in number and are mostly some of the most well known people to exist throughout history - one such person is the "Sword Pillar"
𝐌𝐚𝐠𝐢𝐜 𝐌𝐚𝐧𝐢𝐩𝐮𝐥𝐚𝐭𝐢𝐨𝐧 - one of the important skill of any mage is the ability to manipulate their mana fluidly and freely. It's something that no one who is at the top lacks, and something that every experienced combat expert advises to beginners to work on. Not only does it help in reinforcing your body parts in need, it can help someone attack with unpredictability and also help in manipulating their elements, (kinda like avatar) although the manipulation part is done with the help of mental energy for a lot of starters.
Mana Type - Everyone has different type of mana. To be precise- they have unique properties. There do exist people without such a privilege.
For Ex- Renley's mana is sharp, Len's mana divines danger and opportunities, Professor Loy's Mana is naturally hard. Magnus Irunstark's mana is magnetic.
𝐌𝐚𝐧𝐚 𝐀𝐭𝐭𝐫𝐢𝐛𝐮𝐭𝐞 - When a person capable of using mana reaches a certain threshold in evolving their core and faces some emotional challenge and reach a certain resolve, it's possible that their mana evolves and gets an attribute out of three possible attributes-
Healing mana - pouring mana on an injury causes it to heal, and can be used on others as well.
Concealment mana - abilities used from invisible attribute mana are invisible and insensible.
Destruction mana - attacks from such mana can destroy anything including normal mana.
𝐌𝐞𝐧𝐭𝐚𝐥 𝐄𝐧𝐞𝐫𝐠𝐲
Mental energy is an energy that seems to exists only in humans, and humans capable of thinking normally at that- also known as 'Energy of the mind', while it is possible to used by every being. Unlike mana, it isn't present from birth and is unlocked after one goes some sort of 'maturing of mind' or 'enlightenment'.
It is sometimes said to be the 'manifestation of will or mind'.
How to increase the amount-
It increases passively or when one meditates with focus, the former method is very very slow and the latter method is quite slow as well. Exhaustion of mind and anything that improves the brain and will are good methods.
To strengthen it- use it to lift things you cannot lift with it....yet.
It's like exercising the body- try lifting weights you find tough to lift, one day it'll become easy.
The fastest method to increase and fortify M.E is by going through harsh challenges and traumatic experiences, both of which require strong mental fortitude to face.
The use of mental energy is ungraded and can depend on person to person, for example, a first order sorcerer could defeat a sixth order sorcerer in a battle of mind but that's assuming he doesn't get one shotted and the other sorcerer doesn't focus on mental defence instead of fighting with the mind.
The abilities of mental energy-
Telekinesis- anything can be lifted by covering the object completely with mental energy. The power of the telekinesis depends on the amount used and the strength of the mental energy- and the weight and size of the object -
If not strong enough, one would not be able to move objects of high mass regardless of size and if one doesn't have enough, they wouldn't be able to cover gigantic objects regardless of mass.
Mental energy can't be split from the mind so it works like energy tendrils. At least that's what was thought but one person exists who can split mental energy allowing them to cover the whole world while standing still.
Sense and Scanning- Covering any object with mental energy also allows the user to 'feel' the object and scan it. If paired with some mana- can produce special effects. For eg, Fire mana + M.E = Heat vision.
(It's not possible to 'see color' and is just like touching something.)
Mind Invasion- It's possible to invade one's mind and sense the target's feelings and some talented and strong people can even read or see thoughts to some extent. - this ability is very advance and high leveled.
Intent and Interference- Intent is the ability to project emotions upon someone- for eg. if person A wants to kill person B, if he projects M.E on B, it could make B 'see' images of his death that A wants to do and give A a psychological advantage- can directly cause targets to faint in cases.
Interference is used to break someone's focus by forcing M.E on them. opponent must use their own M.E to counter.
Can be used to disrupt spells when advanced to a very high skill.
Very advance skills -
Sense zone- Spreading M.E in an area and sense everything within the area
Flight - For some reason, it's insanely tough to use telekinesis on oneself and fly, It's like trying to stand in the air by lifting your legs with your hands.
Magicists have theorized many reasons but none has been proven true till date.
𝐌𝐚𝐠𝐢𝐜 𝐀𝐛𝐢𝐥𝐢𝐭𝐲/𝐌𝐚𝐠𝐢𝐜 𝐓𝐞𝐜𝐡𝐧𝐢𝐪𝐮𝐞- After some humans and all demons turn 10, they can awaken a 'magic ability/technique' which is suited according to their desires, dreams or emotions during the moment of awakening.
The abilities allow them to do more than just elemental manipulation and is what changes ranking dynamics.
Techniques could be anything and are usually connected to one's element but pure mana core mages can get the ability to use elements with their ability.
To explain what they are is nearly impossible. But I'll give some example on what they can range from - so little spoilers ahead
1. Fire mage Ash Highfyre's Technique 'Fire Link' allows him to ignite green flames through whom he can pass. To be clear, if sets a green fire from his technique in place A, and sets one in B- if he jumps in place A fire, his body burns to ashes and reconstruct in place B, which allows him to 'teleport' place by place and also heals him.
Limits- each 'link' takes mana and causes Ash to lose mana at a rapid pace, especially if there are multiple links and another limit is that he has to endure a lot of pain since his body kinda.....gets burned.
2. Jack M'ane's technique - The Gambler's secret.
The technique is activated when- and allows Jack and his opponent make a bet, the opponent can choose any indoor game they want- and locks his opponent's mana so that they don't cheat. The bet is then inforced by laws of magic themselves.
Limit - technique activates with a bet...and doesn't help in physical fights, requires Jack to be skilled in the games his opponent choose.
3. Professor Loy's technique - Brackets
Allows him to create barriers that work like brackets, if he is outside- he can divide, multiply the mana of people inside the bracket.
3 types of brackets- parenthesis, curly, square
Limits: If the equation inside is solved, bracket breaks automatically
I won't list much about everything now.
Abilities can evolve to become even more powerful...but that's very rare.
Protagonist Nier Silvernova's ability is an eye ability- when he pours anti-mana in his eye rune- he is able to see collected mana and can negate magic circle with a look.
If he directly negates magic circles- can copy those spells
Limits - mana consumption is enormous and cannot maintain the ability for much long...yet and can only hold five copied spells and after filling the spots, if he uses negate than he'll lose one of those spells.
Side effects- Techniques can have side effects other than main abilities, Ash's ability to heal from regeneration and Nier's ability to copy spells are examples of side effects.
𝐒𝐩𝐞𝐥𝐥𝐬
They are pre-coded commands of sort engraved on mana cores by mental energy. Only a limited number of spells could be engraved.
Simple example of what it allows- A fire sorcerer can manually create a fireball by pouring out mana- condensing it- it lights up- shaping it- shooting it.
If he engraves a spell of the same commands, all he'll need to do is to activate the spell- a magic circle is conjured where the user aims- a fireball would instantly spew out of it. In theory, one can use spells without engraving them but the magic circles cannot be understood by anyone so they can't do it. Except Nier whose ability to negate spells grants him analysis of the spells but he doesn't have the capacity to hold more than five spells in brain.
Conditions - setting limits can allow spells to strengthen but also give variations in the spells.