Some time ago I outlined steps for creating rational magic systems . In short, a magic system is rational if it follows a consistent set of metaphysical laws. This prevents plot holes , reduces the need for foreshadowing , and makes magic feel less contrived

Unfortunately, some magic systems are easier to rationalize than others. If you’re designing a unique system from scratch, you should have little trouble. If you want magic that’s inspired by tradition or folklore, you’ll have a tough time. That’s because folklore contains a slew of eclectic components like potions, pentagrams, wands, chanting, and crystal balls. That’s why stories using traditional magic, such as the Harry Potter series, usually have arbitrary systems instead of rational ones.

However, it is possible to create an eclectic yet rational system. I’ll walk you through my method for doing so.

List Your Requirements

My previous directions started by creating metaphysical rules, and then they extrapolated spellcasting practices from those rules. This method works great for many systems, but if you need spellcasting to proceed in a specific and complex way, you’ll struggle with it. So this time, we’ll start with the results and work backwards. That means the first thing you need to do is list everything you want to see in your system.

Components

The most important part of a magic system is its components. A component is anything that affects the outcome of a magic spell. It could be:

Tools, devices, or ingredients

Behavior by the spellcaster

Symbols or spoken language

Special conditions, like a time or place that are important

Other requirements for doing magic, like being of a particular bloodline

Make a list of your components. Put anything you want to be interchangeable as one item on your list. If every wizard must have a staff, that should be it’s own item, but potion ingredients that differ depending on the spell should be listed together.

If you have more than one method of casting magic in your system, such as one for wizards and one for witches, make separate lists of the components wizards use and the components witches use.

Special Limits and Abilities

Once you’re done with that, list any special rules for what magic can or can’t do in various circumstances. If you have a protagonist with a special magic talent, mark that. If spells inherently can’t destroy matter or heal someone who’s injured, put that down.

Outside Magic

Finally, make a list of anything with magical effects that are unrelated to spellcasting. Magical creatures are the mostly likely candidates for this list, but maybe your world has a sacred floating rock.

While listing your requirements, avoid tying yourself down. The goal is to articulate everything you already need, not to decide what you should have. If something you put down is optional, mark it as optional. The more items you have, the more work you’ll have to do. Plus, you’ll want room to make changes in later steps.

Example In my example world, magic is cast by both witches and wizards, but their casting is themed differently. I want classic high-tower wizards and witches that are nature-focused. Wizard Components Every wizard has one staff

Wizard rely on spellbooks they read from or memorize

Crystal balls and other shiny devices are used in casting Witch Components Pentagrams or other symbols and diagrams should be drawn in large on the floor

Spells use natural ingredients, like eye of newt or crow’s feathers

Witches should have reasons to cast at specific times, like the summer solstice or during an eclipse

Witches should cast magic in groups as well as independently Special Limits and Abilities I have a protagonist that I want to be unusually powerful, but I also want it to be dangerous for her to do magic – risking herself and others. I’m imagining a scene where a character casts a spell by dancing. I want this to be awe-inspiring and therefore not something most spellcasters do. Outside Magic I want unicorns, werewolves, and angry spirits in my setting.

Choose Spell Functions

Now you’ll create a pool of spell functions that your components can perform. The most obvious of these is shaping what the spell actually does. In many eclectic systems, it’s possible to do anything with spells. If that’s the case for your system, I recommend adding just one function for this: “Determining the overall effect of the spell.” Otherwise it will be difficult to subdivide all the possible things your spells can do into functions that make sense. If the scope of effects is smaller, you can look for ways to subdivide that feel natural.

Even if you have different groups of casters with different methods and theming, do your best to pick functions that are thematically similar. Especially avoid giving yourself two different functions that basically do the same thing but with different themes. For instance, you might want “appealing to a higher being” or “connecting to a power source,” but don’t choose both. This kind of redundancy will fragment your system, making it feel more arbitrary.

I’ll give you ideas here, but you can also create your own. Pick as many as you want from any or all of these categories. The more you pick, the more complex your system will be. That means you’ll have an easier time using lots of components, but your system may become too complex to explain in your story.

Shaping What the Spell Does

Determining the overall effect of the spell

Giving the caster power over a specific element

Moving something through space or time

Changing one substance into another

Giving or destroying life

Affecting the Target

Choosing the target of the spell

Creating a conduit between the caster and the target

Overcoming barriers between the caster and the target

Powering the Spell

Getting the attention of a higher being

Pleasing a higher being

Providing a power source

Providing a connection to a more distant power source

Making reality malleable enough to influence

Altering the Spell’s Execution

Speeding up the casting time

Making the spell last longer

Allowing a longer range

Reducing energy usage

Strengthening the effect

Aiding the Caster



Improving concentration

Providing a focus for meditation

Keeping the caster’s soul from getting lost

Protecting the Caster

Fighting off spirits that might attack the caster

Keeping the caster hidden from malicious people, creatures, or spirits

Making it difficult for the spell to be traced back to the caster

Shielding the caster from magical side effects

You might notice that these functions suggest a lot about the magic system and where it can go wrong. If you create a function that’s “preventing casters from being compacted into a 1cm cube,” then congratulations, you now have a magic system that will compact people into tiny cubes.

Like for the previous step, don’t write this in stone. You’ll want to make changes as you go.

Example Since I have angry spirits in my requirements list, I think I’ll go with a spirit theme. I’ll also use higher beings, which feels similar. In my previous post on rational magic, I warned that higher beings will complicate things. However, when your system is already complicated, higher beings will make it easier to explain. Who knows why the gods want what they want? So here’s the functions I’m starting with: Determining the overall effect of the spell (I’ll include identifying the target in this)

Keeping the caster’s soul from getting lost

Getting the attention of a higher being

Pleasing a higher being

Fighting off spirits, maybe hiding from them?

Speeding up casting time

Match Functions With Components

Now it’s time to map your functions to your components. You might have noticed that I didn’t tell you to pick as many functions as you have components. That’s because this is a messy process, often involving revisions to both sides. If you have exactly the right number, that will just discourage you from making positive changes.

Remember that in addition to adding or removing components or functions to create a nice match, you can also group them into more general categories or subdivide them into more specific ones.

When making matches, ask yourself these questions:

Are optional functions matched with optional components, and are essential functions matched with essential components?

If the component has a lot of variety, like potion ingredients, does the function also have a lot of variety, like spell effects? If not, can variety be added or removed?

Is it easy to explain why or how this component would perform this function?

If you have more than one component list, each list should match the same set of functions. Then you’ll need to explain why one group of casters prefers one component for that function, and the other group prefers the other. Tradition or culture is a sufficient reason if both components are equally practical. If one component is more flexible or powerful, you’ll want to give it a disadvantage as well.

Example I’ll go through all the matches I made and the reasoning I went through to get there. Protection from Angry Spirits – Staff and Pentagram Because I wanted both the wizard’s staff and the witch’s pentagram/diagram to be present with every spell, I decided they should perform the same function. So I gave them the task of protecting the caster. The regularity of these components suggests angry spirits are common and dangerous, which will raise conflict in my setting. However, the components don’t need to perform this function exactly the same way. I decided that a pentagram hides the caster from spirits, whereas the staff is actually a spirit weapon that both deters spirits and fights spirits off when they aren’t deterred. Unfortunately, the staff feels more practical than the pentagram. I want my pentagrams to be precisely drawn on the floor with lots of symbols, and who would do that when they can just grab a staff? So I’ll add a cost to the staff. Effective staffs can only be made by giving up part of the caster’s spirit – effectively erasing an important memory or an aspect of their personality. Witches don’t want to do that. Strengthening the Effect – Casting on Specific Dates and Times I want my witches to have a special reason to cast magic on the solstice, etc, but I still want them to be able to cast when it isn’t the solstice. So this component needs to be optional. I have an optional function in my pool – speeding up the cast time – but waiting for a specific date to speed up casting time doesn’t make any sense. So to match it to an optional function, I decided to trade in “getting the attention of a higher being,” which feels mandatory, with “strengthening the effect.” I’ll say that the attention of a higher being is just a given, since the higher beings can keep their attention on everything at once. Strengthening the effect will also give wizards a reason to cast at specific times, but I’m okay with that. Pleasing Higher Beings – Natural Ingredients and Cool Devices Since higher beings are powering the spells, they’d better be happy with the caster. I decided that the natural ingredients and neat devices are gifts meant to please a higher being. I imagined the wizards using the devices rather than gifting them, but maybe the wizards use the more complex devices for their non-magic scholarly pursuits and gift shiny materials like gems or coins. Because my components have a lot of variety, both between witches and wizards and from spell to spell, I’ll also need to add variety to my higher beings. I’ll say the higher beings available to power spells are numerous. Each being likes different things, and each is better at certain types of spells. Witches and wizards technically have access to the same beings, but witches prefer some and wizards prefer others. Knowledge about these beings is kept secret, and no one is familiar with all of them. Determining the Overall Effect of the Spell – Spellbooks and Chanting Written words or chanting has even more variety than ingredients or devices, so I decided to pair it with my most varied function – the effect of the spell. This is essential, so witches will need an equivalent. They’ll sing during their rituals. I don’t want casters to say their spells in English, so I’ll say that the higher beings have their own language. However, I want spellbooks, so I need a reason wizards don’t casually speak whatever effect they want. Since it’s the language of higher beings, I’ll say it’s immensely complicated and no one has a good enough grasp of it to ad lib. They have to memorize phrases that have been carefully figured out beforehand. Wizard record these phrases in spellbooks, and the songs of witches are passed down from generation to generation. Keeping the Caster’s Soul From Getting Lost – Personal Item I don’t have anything that’s a great match for this function, so I need to add an additional component. Casters should have an item with strong personal meaning. This will anchor them and help them find their way back after venturing into the spirit realm to connect with a higher being. It could be as big as a place with special meaning or as small as a piece of jewelry. After some thought, I’ve realized the wizard’s staff could easily perform this function as well as being a weapon against spirits. It has a piece of the wizard’s soul, after all. So this personal item will only be a separate component for witches. Strengthening the Effect – Multiple People The last things I have left are “speeding up the casting time” and “witches should cast magic in groups.” They are both optional, but a match between them doesn’t make intuitive sense. Unless casting normally takes days, and I don’t want it to, using everyone’s time for a shorter ritual isn’t much of an advantage. So I decided to trade in that function for strengthening the spell’s effect. I’ve already got this function, but that’s okay, more than one thing can strengthen a spell. Plus, this gives me a great reason for big witch parties on special occasions, and I like that. However, I don’t want wizards to team up very often. I’ll say there are fewer wizards, and except for rare apprenticeships, they live far apart. They are also competitive. That means they will still gather if they need to, but they won’t want to in most cases.

Bring It Together

You should have lots of details for your magic system. Now you’ll create the big picture. Write down how your magic system works from start to finish. If the pieces don’t fit together quite right, try changing the explanation you used for one of your matches. If you need to, you can edit your matches. Do your best to keep the inner working following similar themes, even if magic is expressed and cast in different ways.

This is a good time to extrapolate new information. Look for gaps in your functions. Maybe you have a function that directs energy but not one that supplies energy. That’s fine, it just indicates that casters get energy without effort. Maybe every person is their own energy source and complications in providing energy rarely occur. Each function you do have implies a way for spells to go wrong. What things could happen if a caster botches a component and impairs its function? Your choices will add fun conflicts to your story.

Once you’re done, review what casters are capable of doing. Make sure they can’t always get what they want, and that they can’t destroy planets or do anything else that’s powerful enough to break your plot.

Example Over hundreds of years, witches and wizards have passed down the knowledge of powerful beings in the spiritual realm. With knowledge of a powerful spirit, a witch or wizard can gather gifts from the physical realm that it likes. If the witch or wizard enters the spirit realm, pleases the being with its favorite things, and asks for a favor in the spirit language, the spirit will usually grant that favor. Different spirits are more or less inclined to different types of favors. Powerful spirits are more inclined to make an effort if they are flattered by a greater number of people or if they are asked during times they are particularly powerful or active. But there’s a limit to how much these powerful beings can or want to do. Asking too much looks presumptuous. And unfortunately, the wrong items or words could insult the spirit, at best creating no result and at worst incurring its wrath. It takes years of training before witches and wizards can create a doorway to the spirit realm, allowing their souls to cross the barrier and speak to a powerful being there. When this process goes well, the soul stays closely tethered to their body. Witches and wizards stay in control of their body, and when the soul sings and chants, the body does also. To the witch or wizard doing magic, the spirit realm appears overlaid on top of the physical realm. When this process does not go well, the soul can wander too far from the body, weakening the connection and causing the soul to get lost. When this happens, the body slips into a coma. The soul then searches for the beacon that is their personal item or staff. Depending how long it takes them to get back, the body could remain abandoned for a minute, an hour, or forever. A vacant body is a tempting target for spirits. And unfortunately, the doorway acts like a beacon for all sorts of lesser spirits on either side, many of them malevolent. If the witch or wizard is not careful, dangerous spirits could come to the physical realm. Spirits might attack the spellcaster’s soul or claim the body while the spirit is preoccupied or lost. Witches solve this problem by drawing large circles and symbols in the spirit language around the caster. This confuses most spirits, making them think the spirit doorway is an entrance to the home of a particularly powerful being. Wizards cast their very first spell in conjunction with the master who taught them. This first spell separates part of their spirit and shapes it into a spirit weapon that lives inside a staff they’ve crafted. In the future, any spirits nearby will notice there’s a weapon that can be used against them. This usually deters them from attacking. In addition, the staff acts as a beacon for the wizard’s soul, should it get lost.

Branch Out to Cover All Requirements

Now you should have metaphysical rules for all the components of spellwork. But you probably have more requirements to cover. Look for ways to use what you’ve created to explain the rest of your requirements. You can revise your budding system if you have to, but in most cases, adding more nuance or complexity will do the trick.

Example For my powerful protagonist, I’ll say she’s actually a former spirit being. After she was involved in a big conflict between powerful spirits, she fled the spirit realm for the safety of the physical realm. She can’t do magic on her own anymore, but she has friends on the other side. Not only will these friends will do bigger favors for smaller gifts, but she can speak fluently to them. Unfortunately, she also has enemies that will seek her out.

Next I’ll cover the magic dance scene I imagined. Dance is a form of expression like language. I’ll say that some of the spirits speak a different language, and, in particular, an important being has a language of not sounds or symbols, but movement. This spirit must be spoken to with dance. Only the relevant character knows this spirit or its language.

I’ll say unicorns are magic because they are the chosen creatures of one of the most powerful spirit beings. This is one of the spirits that created the world long ago.

Werewolves might be the descendants of one or more spellcasters that enraged a powerful spirit and were cursed by it. This spirit gets stronger as the moon waxes, making the curse most severe on a full moon.

My angry spirits don’t need an explanation – spirits are clearly an integral part of the setting and the source of magic itself. However, my system implies that many lower spirits could be the lost souls of former spellcasters. Maybe these spirits are especially inclined to steal a body. This creates a lot of plot opportunities.

That’s it, my system is done. While my system is very spirit focused, my stories don’t have to be about spirits. While witches and wizards will care about spirits, an onlooker to a magic ritual would just see witches singing in a circle of symbols or a wizard chanting with their staff and shiny objects.

Explain your rules to the level that fits your story. Hiding how your system works will keep your magic wondrous and mysterious, explaining more allows spellcasting to be central to your plot. Either way, you’ll be able to maintain the flavor of magic you want while benefiting from a solid set of rules.