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 that allows them to absorb mana in the surroundings, convert the said mana into usable elemenal mana or usable pure mana and store the usable mana in their inner domain. (basically dantian if you've read enough xinxia, I'll use dantian in the main story..because it better describes itself)

The core is also present inside the Inner Domain that 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.

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 three types- natural, unique, supreme.

Some natural elements - fire, water, earth, wind, metal, blood, lightning, wood, ice....etc.

Some unique elements - storm, forest, holy, shadow...etc.

Some supreme elements - light, space, death, star...etc.

Elemental cores also hold the properties of the element they represent, for eg. Fire element core would be hot, light elemental core would be shining bright like a sun...etc.

To use the elements, a mage pours out their mana out of the domain 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 rate of which can be changed as one trains enough.

Some people can use all their magic without any loss. Such people are countable in fingers 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 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.

Invisible mana - abilities used from invisible attribute mana are invisible.

Destruction mana - attacks from such mana can destroy 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', 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.

Mental energy is divided into 5 stages - 1 to 5 with 1 being the highest. No sub-rankings are made as it isn't possible.

Each grade is representative of the amount-and-strength of the energy and someone from grade 1 is said to have very high amount of mental energy and strong energy.

Grades of mental energy don't necessarily represent 'power' as it is only one of the factors. But for most part, stronger people have higher amount and stronger mental energy.

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.

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 (why is this information important? I wonder...)

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, only grade 3 and above can do it. Works best on weak minded people.

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 - stage 4 or above

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 - stage 2 above-

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, however it's much easier to manipulate one's own mana. 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 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 to use elements.

To explain what they are is nearly impossible. But I'll give some example on what they can range from - so little spoilers ahead.. or you can think of magic techniques like jujutsu kaisen curse technique and not read some of the technique

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.

Techniques can evolve to become even more powerful...but that's very rare.

MC 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 anytime he negates other spells, he loses previous copied 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

Conditions - setting limits can allow spells to strengthen but also give variations in the spells.