How can I flesh out and balance my magic system based on the 7 deadly sins and heavenly virtues?

Question

Context and concept

The Big Bang occurred and the stars started to form and go supernova spreading the elements that were within them far and wide throughout space. The solar system, including the Earth and the life upon planet Earth, is thought to be made of this star dust. In my world an additional element was formed that ordinarily can't be observed by humans, Metatron. It's a type of metal whose atoms are present in every living thing like how carbon is. The special characteristic of Metatron is that it reacts to and is manipulated by the thoughts of sentient creatures. When this happens the thoughts and the Metatron merge to form a new substance called Phantasm, which can then be used as fuel for supernatural powers.

These powers vary based on the thought used and the elemental affinity of the user. Certain thoughts correlate to certain elements and everyone has a base elemental affinity they lean towards. Although additional affinities can be gained through training, a person can only possess up to 3 affinities out of 14 possible elements. Alongside the elemental affinities are the elemental domains which are groupings of certain elements. While an individual might not possess an element affinity on one side of the domain, by possessing an element affinity on the other side of the domain they would still be compatible with using the first elemental affinity in techniques and attacks, albeit with less power than if they were naturally that elemental affinity in the first place. For example, if an individual possesses a water elemental affinity then they would be compatible with ice affinity techniques. Even though they aren't naturally a part of said affinity. Trying to use a technique with an elemental affinity where there is neither power nor potential is, while possible, uses considerably more Phantasm than simply sticking to one's own elemental potential.

The seven domains and the elements they contain are based on both the seven deadly sins and heavenly virtues. The way I have it set up so far is as follows: the base element which can be used uniquely from person to person. The sin as a type of limitation or a bane that should be avoided. The virtue as something that is encouraged for the power. A generic unique property to each domain.

The seven domains are :

Domain of animal and plant life

Users of this domain are especially feared as the organic life they create or manipulate can overtake another person's Phantasm powers and constructs by "devouring" them. This is done by converting the enemy's Phantasm into their own. Skilled users of this domain can even control their enemies directly through the same principle by converting the Phantasm in their enemies body into Phantasm they can control. While extremely powerful, users of this domain must have temperance. As devouring or controlling an amount of Phantasm beyond their capacity will cause the destruction of their organic focus as well as severe backlash in their own mind and body.

Base elements are animal and plant life with the sin to be avoided being gluttony and the boon being temperance. The ability to manipulate people is the unique property for this domain. 

Domain of fire and poison

With fire that threatens to char them or poisons to corrode their being, users of this domain must practice patience so that they don't overheat or overdose on their own power. Such an attitude is rewarded by eventually becoming immune to poisons or using flames to cauterize wounds.

Base elements are fire and poison with the sin to be avoided being wrath and the boon being patience. I don't really have a unique property for this domain...

Domain of light and aether

The domain is about strengthening lifeforce such as making things burn brighter and hotter or make an object stronger and more durable. Users of this domain have the innate ability to share their Phantasm with others often through the form of healing or support techniques. Such sacrifice is not unrewarded as the amount of Phantasm expended will return multiplied exponentially. While powerful it is not without its risks and limitations. Users of this domain must be careful not to save up too much Phantasm than they can handle. Regardless of the power it brings, such avarice will only cause their own destruction. 

Base elements are light and aether with sin being greed and virtue being charity or sacrifice. Healing or other support techniques (think stuff like boosting certain stats in a video game) are the unique power.

Domain of earth and metal

Users of this domain aside can instantaneously create weapons or items. While it is possible to create Metatron, it is generally considered not worth it due to the large amount of Phantasm it consumes as well as the incredible stress it puts the mind and body under. Objects if conjured out of pure Phantasm will deteriorate after a while like all Phantasm constructs, and will revert to their original state if it was a manipulated material. There is a way to increase their longevity and power, by giving or sharing these objects to others. While highly valued there is a great risk in using these abilities. Users of this domain must have a generous heart as the items or weapons shared in this way are still connected to them. An imbalanced emotional state or being filled with envy will cause the item in question to become a cursed object that harms its current wielder and drains them of their Phantasm. Often resulting in death for both parties.

Base elements are earth and metal. The sin is envy and the virtue is kindness or generosity. The unique property of this domain is the ability to create special objects that can be shared with others to become even more powerful.

Domain of darkness and void (negation)

Whether covering themselves in shadows or negating their presence, users of this domain are at their strongest when they are hidden or concealed. They can choose to further limit themselves by imposing restrictive rules on their abilities. While doing so will hamper them in some way, the greater the restriction the greater the power is gained in return. Many users are famous as exorcists who can negate and restrict not only their own Phantasm but others as well. They must be careful as being consumed by the lust for power and control over others will leave them unable to conceal themselves and thus vulnerable to attacks.

Base elements are darkness and void. The sin is lust (in this instance lust for power or control) and the virtue is a type of abstinence or self-restriction. The unique property is being able to purify others' Phantasm abilities.

Domain of water and ice

Users of this domain must have diligence and show great effort in using their techniques. Being lax in control and persistence will result in the elemental effects overwhelming them. Symptoms of water toxicity or even being frozen alive can occur if one is not showing a good work ethic in using this domain.

Base elements are water and ice. The sin is sloth and the virtue is diligence or persistence. I haven't come up with a unique property for this one yet...

Domain of wind and electricity

Considered the most arduous domain to use and master, users of this elemental affinity must learn to submit and show deference to let the power guide them into their techniques. Being arrogant enough in trying to bend the elements to your complete control will only result in your body being thrashed about or torn apart.

Base elements are wind and electricity. Sin is pride while virtue is humility or deference. I haven't come up with a unique property for this one either...

Question

As you can see I'm having trouble coming up with unique properties for some of the domains. I'm also worried that some of the unique properties are not strong enough when compared to the others. What I'm looking for are ideas for the unique properties of domains that aren't specific to one of the elements inside said domain. For example I originally had the idea to make the domain of fire and poisons unique property be a cure for ailments. But I rejected that idea because only the poison element worked and wasn't a generic enough concept to work with fire as well. In addition if it's not too much trouble I'd like some feedback on the magic system as a whole. The overall concept as well as what could be changed.

Answer 1

Animal/Plant domain

This should probably only allow the control of non-person Phantasm. The higher sentience of humanity allows for manipulation and control of lower sentience but cannot forcefully intrude on same-level sentience.

Gluttony/Temperance still applies. Unique Skill: Animal/Plant Control

Fire/Poison Domain

Looks good. The unique property would make sense to be something like purification as in most mythos Fire burns away impurities and Poison in small doses usually can be transformed into antidotes.

Wrath/Patience still applies. Unique Skill: Purification/Antidote

Light/Aether Domain

Personally, I think the ability to enhance others is enough. Perhaps combining it with weakening their personal usage of their element would create the desired scenario of having them primary spending it on others.

Greed/Charity still applies. Unique Skill: Buffing

Earth/Metal Domain

I would make one alteration. The reason they should share their constructs is because there is an upkeep in phantasm to their creations. The cost need not be spent by the creator. Instead, Others can pour their Phantasm into them to keep them stable.

Envy/Generosity works but, Envy should instead make it hard to focus Phantasm into items. Being envious of anothers tool will make Phantasm naturally flow to the object of Envy rather than their own creations. Unique Skill: Object Creation.

Darkness/Void Domain

The self-restriction aspect is neat. Personally, I would make their ability twofold. Manipulation of darkness to restrict others sight and a restriction of abilities to void the strengths of others. The danger being that all restrictions placed on others apply to themselves as well. So they must be conservative with it or risk being as helpless as a babe themselves.

Lust/Abstinence still apply in the same way. Unique Skill: Negation.

Water/Ice Domain

Water and Ice are naturally unforgiving. Tsunamis, glaciers, oceans, swamps, and mountain tops all come to mind. The power contained within that element is very strong and the reason diligence is needed is because they are wide area elements. Lax attitudes when using them will get yourself or allies injured. Naturally leeching Phantasm from the surrounding area could be a natural property that can be controlled with practice thus reinforcing the need for diligence. Don't want that ice spike to accidently turn into a new glacier.

Sloth/Diligence still applies. Unique Skill: Leeching: draws Phantasm from the surrounding area.

Wind/Electric Domain

This one was pretty vague but, trying to control where the wind blows or the path lightning takes from point A to B is a fool's errand. The best your practitioners can do is designate a direction for wind or designation positions A and B. Given the humility/deference theme, having them be able to reduce the effect of a harmful Phantasm ability by letting it flow through and guiding it rather than controlling it. This allows them to send the ability back as a counterattack. They are still harmed but they are harmed less than if they pridefully tried to block it.

Pride/Humility still applies. Unique Skill: Counter.

Balancing

Balancing is a difficult task. Sometimes balancing isn't done by making all abilities having an equal power level. Power balancing could be done by the number of users a particular domain has. Void Domain way too strong? only 1/100 domain users are void users or 1/1000. I would personally thing that how these domains are used would be more important than what their powers are.

Answer 2

Follow the paper-rock-scissor schematic

It's an old, true and tried game-design trick used in most multiplayer games to balance them out, whether they're action or strategy ones. Here's the method I like to use, it's not perfect but it can still help you :

First draw a circle made of 7 bubbles linked by arrows going around, as much as you have elements. Then, lay out the elements and unique attributes in each circle, according to what you wish to make. It might very well change along with your ideas, so use a pencil or post-its to reorganize them.

Put first the domain you're the most sure about its defining properties, then, if you have it, another one in the bubble next to it, either as a countering domain or a countered domain. Write down on the arrow in two or three words why you think the domain the arrow comes from is stronger than the domain targeted by the arrow, using the unique caracteristics of this domain (including unique properties).

An example using your domain (among many others)

So I'll get you an example using 4 domains, as to not clutter my answer with over-informative information :p.

For this example, I'll use light/aether (shortened to LA), earth/metal (EM), Wind/electricity (WE) and fire/poison (FP)

I went for this circle, starting with LA as it is for me a domain I can easily see it, being accustomed to the role of healers in RPG games. So we have :

LA->??->??->??->LA.

Now, what could be relatively stronger than light, which has the duality of "giving/keeping"? I'll take Fire and Poison, as I think that the Fire and Poison is able to alter and destroy slowly (or patiently if we keep your duality sin/boon) the phantasm used, rendering any kind of propriety to it inoperant and worthless. That's a strong counter, as whatever your light mage will try to do, it will become weaker and corrupted by making "giving" an useless act at best, and a damaging one at worst.

LA->??->??->FP--Corrupt-->LA

Continuing to climb back the loop, I look at the remaining options : Wind/Electricity and Earth/Metal. Don't be surprised, it will become harder to choose, as you try to tie the two end of the loop together. Ok, I've thought it through, I'm more keen to choose earth/metal as the counter to fire and poison. Why? Because objects made by this domain are impervious to the poison and fire, creating a safety range that cannot be breached through. Like how being generous takes you a step back from anger, and how being envious can make you wait a lot more than patience could do.

LA-->??->EM--Impervious to-->FP--Corrupt-->LA

Last element is Wind/electricity. It's the hardest part since we need to find a weakness and a strength. But remember, it doesn't necessarily need to be about the same thing. Here, as much as being generous is important, it "shows off" your possessions, focusing too much on them rather than what you are. Wind and electricity can run through and around earth and metal items to strike directly at the target's core. Regarding light and Aether, being too much humble can make you forget you can do great deeds, even if it means making you look more than you're willing to. Light and aether, by its enhancing properties, deviates any wind or strike by making the person stronger than the wind and more resilient to the pain induced by lightning as they brace themselves to give their all for the others.

LA--Endures-->WE--Strikes around-->EM--Impervious to-->FP--Corrupt-->LA

See how I went through the process? Think of what makes it unique, then strike it down as strong as you can with another one. And because you work on what makes your domain special, represented indirectly by the words on the arrows, you also get the chance to develop unique properties :).

Watch out for unknown counters

After you've put down your domains and strengths/weaknesses, check that there is no arrow you can make between seemingly unrelated domains, and adress those if you have a lot more arrows going toward a domain than going from. It probably means that your element is weaker than the rest.

For this part, I strongly recommend to get in touch with several people who can give you their opinions and another points of view on the matter, notably to find the invisible arrows on your graph. In the end though, it's you who make the call based on what you prefer, not them. it's because you are the one writing the world, and if your world is taken out from you and to their hands, you will risk losing the morale to continue.