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consider these variables carefully

I’ve been building magic systems for a long time — since before I could read — but it wasn’t until I got serious about writing that I paid attention to my process. Suddenly, I wasn’t making magic systems for fun anymore. I was making magic systems for my stories and I wanted them to be the best they could be. So I started digging.

And I found next to nothing. There was general advice, lists of questions, and Sanderson’s Laws of Magic, but nothing like I was looking for. I wanted a documented process with a defined list of steps to take and stages to work through. I’ve spent years trying to rectify that with this very blog.

But what does this have to do with these five, oh so important magic system variables?

Magical effects determine what your magic-users can do, but magic system variables are the sliders, buttons, and dials that make your system what it is. There’s another post that goes into the general details of What You Need to Know About Magic System Variables, but let’s start simple. Here are the five most important magic system variables of them all: Transference, Rarity, Consistency, Knowledge, and Source.


The transference variable determines how the magic effects and abilities of your system are gained, lost, given to, or taken from a magic-user.

transference is the most important magic system variable

Now, we could start asking an endless stream of open-ended, difficult to answer questions until I am curled up on the floor crying, but it would be nice to change my bedtime routine up a bit.

Rather than consider the endless array of feasible solutions, I like to concentrate it all down into a sliding scale from extremely low to extremely high levels of transference. Our job is to figure out where you want your system to sit on that scale.

The Dark is Rising by Susan Cooper is a perfect example of a system with little to no transference. The protagonist, Will Stanton, is a guardian and warrior for the light chosen to fight the rising darkness. His powers don’t come from an established ceremony or special concoction, but because he is the seventh son of a seventh son. There was no way to control who has the power and no way to change it once it has passed.

Now set the transference to the other end of the scale, and what do you get?

You get magic that can be bought, sold, and traded to anyone and everyone. Potions, enchanted weapons, and personal force-fields are all examples of a high transference system. Anyone can pick up a bottle, shirt, or sword and suddenly they can produce magical effects. If you want magical technology in your story, it will need high transference.

Your system will most likely sit somewhere in the middle. Just remember, the more control people have over who can produce the magical effects, and when they can do it, the higher your system’s transference. Let’s take a look at this next variable.


rarity is another important magic system variable

When determining the rarity of your magic, you need to ask the age-old question, “How common is the magic in your world?”.

It’s an important question you need an answer to, but it’s only the start. Rarity also determines how many forms of magic exist in your world, the percentage of magic-users among the population, and where it can be found around the globe.

The rarity of any magic system exists on a scale. At one end, the magic-users and magical effects are limited to a few rare cases. Take Nightmare on Elm Street, for example. The story of Freddy Krueger and his return to hunt children in their dreams is exceedingly rare.

On the opposite end, the magic is commonplace and can be found anywhere and everywhere in the world. The Codex Alera by Jim Butcher is extremely common (low rarity) because every Aleran has access to furycrafting. Well… almost every Aleran, but you get the point.

If a magic system sits in the middle of the spectrum, it should be common in the world but still isn’t everywhere or available to everyone. The Obsidian Trilogy by Mercedes Lackey and James Mallory is an excellent example of this, where a few select mages rule over the primary city of man. there are also forms of magic-users and magical creatures in the world, but your characters aren’t guaranteed to meet one.

The rarity of your magic can massively impact your story and your world. As such, it is one of the most important magic system variables to address along with transference. Next, let’s look at the consistency of your system.


This variable is exactly what it sounds like and determines the repeatability and reliability of the system and the magical effects it produces. Simple as that.

If the consistency of your magic is low, then the magical effects produced might be random or display a great variety between uses or users. Uprooted by Naomi Novik is a terrific example of a lower consistency system. Different magic-users have wildly different forms of magic (natural growth, summoning, forging magical gear, etc.) and we seldom see the same effect twice.

In stark contrast to Uprooted, we have the crystalline magic/power found in The Aeronaut’s Windlass by Jim Butcher. In Jim’s book, the power and effects of the crystals are replicated, quantified, and manipulated to power airships and cannons alike.

Set this variable however you like, just make sure you understand how it manifests in your system and your world. Now let’s move on to the often overlooked but none-the-less important magic system variable of knowledge.


Yes, this variable influences how many people know about the magic, but it also covers so much more. Where you set your system on the knowledge spectrum influences how many people know and understand about the magic’s inner workings. Can magic-users explain how their magic works and why it behaves the way it does? Are their explanations correct, or are they filled with false knowledge and bad assumptions? Every factor matters.

General awareness of magic is the most commonly addressed portion of this variable. In fact, the entire urban fantasy genre pivots around the concept of the “hidden world.” Consider The Dresden Files by Jim Butcher. Most of the world is oblivious to the supernatural world and even the people moving through it, like Harry, know little in the grand scheme of things.

Things couldn’t be more different in The Alloy of Law by Brandon Sanderson. Everyone knows all about the existence of allomantic and feruchemical powers and the details on how they work. There are even specific careers and services built around people’s understanding and familiarity with their powers.

And that brings us to the last of the five most important magic system variables: Source.


Nothing shocking here. Source is all about where the magic originates, how it flows from the origin to produce magical effects, and how it gets replenished (assuming it gets replenished at all).

I view source a bit differently from the other variables we’ve discussed so far. Rather than being a scale of possibilities ranging from high to low, I think of it as two switches and a text box. One dial flips between internal and external, while the other flips between finite, renewable, and infinite.

With an internal source, the magic or power comes directly from the magic-user as opposed to external sources where it comes from outside the magic-user. Nothing shocking there.

The other switch (finite, renewable, and infinite) determines whether the power source gets refilled over time or is permanently consumed while performing the magic. A finite source cannot be replaced once it is used up, while an infinite source will never run out. Renewable sources are consumed or drained by the magic but will return or recharge over time.

Each piece makes sense, right? Well, the important part comes from how you combine them.

Let’s look at some examples.

The Tech Mages from Chris Fox’s Magitech Chronicles have an internal, renewable source of power for their magic. The power, once gained through a transference process, is pulled from within themselves to fuel their spells and special gear. These internal reserves can be quickly depleted by a fighting Tech Mage but will be refilled over time.

Potions from Harry Potter are the exact opposite, functioning as external, expendable sources of power. The source is external because, once created, there no magical ability is required to use a potion. Anyone can drink one and benefit from its effects. Potions are also expendable sources of power because they can only be used once before a new one must be made.

That just leaves the text box. Where the magic comes from and how it is regained throughout the universe is a complex topic. A slider alone isn’t enough to capture all the details. So I leave myself a place to brainstorm and explore the nuanced details around the source of my magic.

Those Are Your Most Important Magic System Variables

There are lots of other things to consider when building your system. With time and experience, I have found these five to be the most important magic system variables out there. If you deliberately explore and set these variables, you have already done more than most. Next month we will talk about the last five magic system variables. This will arm you with tools and leave you ready to manipulate all ten in your next magic system.

If you’re still itching for more, you should join my newsletter to get a sneak peek at content months before the rest of the world. And if you’re in the throes of building a system, you can always contact me with questions or grab a copy of my new workbook Restrictions May Apply: Building Limits for Your Magic System.

display the magic limitations workbook cover

That’s all for now. The world is a crazy place right now, so please stay safe, stay sane, and stay awesome. Rowenson out.

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