Fate System Toolkit

Pieces of Power

Let’s assume you’ve got an idea for a magic system, and it makes sense on its own. You can explain it in normal language, and you have a rough sense of how it’s going to work in your game. Now it’s time to start thinking about mechanics, and how to represent your system in the game.

As a first word of caution, don’t feel obliged to solve every problem with a mechanic. If your magic system is easily described and clearly understood, it may require nothing more than a skill or two to represent facility with it. Be careful about immediately jumping to the mechanics—make sure there’s a real problem before you introduce a mechanic to solve that problem, and your finished product will be much stronger.

When it comes time to introduce a mechanic, there are two things that the mechanic needs to do—or at least consider—an outcome and a limitation.

Outcome is obvious—you want to be able to throw around fireballs, so the effect handles things like how you target them, how big they are, how much damage they do, and so on. The limitation is less sexy, but more important: it answers the question of why you would do anything but throw fireballs.

What’s important to note is that the entire effect may not exist in only one place in the rules. It will often be threaded into other rules in ways that are often obvious once you look for them, but are easy to overlook if you don’t think about them.

Magic systems tend to be constructed with limitations serving as a frame for outcomes. That is, there will be a broad set of rules that control when and how magic can be used—what spells are known, how often they can be cast, who can cast them, and so on—while the rules for outcomes, like blowing things up with fireballs, are often smaller pieces of rules-text, limited to that particular spell and those like it.

This may seem like a very fiddly distinction, but if you’re designing your own magic system, then this is something you really need to get your head around. The second dial gives you immense power and flexibility when you do your own design, because it lets you choose the axis of change.

As an example, consider the classic system of memorizing spells to cast them. The container—and by extension, the biggest limiter—controls what and how many spells a character can cast, while the outcomes are the individual spells. This allows for a lot of versatility, because you can change the limitations without changing the outcomes—perhaps by introducing another character class that gets the same spells at a different rate—or change the outcomes without changing limitations, by adding or removing spells.

Changing outcomes is no big deal. Swapping out a spell is easily done and easily fixed, and it’s a great way to do cool things. Changing the limitations is a much bigger deal, full of potentially unexpected consequences. It’s also where the real power of hacking lives. Perhaps more importantly, if you understand this division, you understand how you can build an entirely new magic system by changing one or the other, rather than needing to rebuild entirely from scratch.


Limitations usually take one of two forms—use or opportunity. Limitations of use impact who can use magic, while limitations of opportunity speak to how and when magic can be used.

The first thing to consider when thinking about a magic system is who can use it. In fiction, the answer might be “anyone,” but even then it will probably need some form of representation. Setting aside limitations within the fiction, the gateway for using magic usually takes the form of one or more of the following:

  • A new skill
  • A specific aspect
  • A stunt
  • Refresh cost
  • Opportunity
  • Resource cost

Stunts and Refresh

Notice that we treat stunts and refresh as two separate things. This is because they are separate building blocks, and while the default build says a stunt costs one refresh, that’s just one build. If you’re constructing your own system, then you have the freedom to handle them differently.

This opens up a lot of doors in terms of what a stunt is. Practically, a stunt is its own little rule—or rule exception—and while their number and nature are restricted by refresh cost in the baseline, you can break free from that structure. As an example, Stormcallers and Six Viziers both effectively give a bundle of stunts, and only charge refresh for the bundle, basically providing a discount for the thematic grouping.

New Skills

Although adding a “magical” skill seems like the least expensive option to allow magic, bear in mind the opportunity cost—the character is giving up some other skill to pursue magic, so there is a tradeoff. It is possible to fold magic into one or more existing skills, but if you do that, then you’ll probably also be demanding some other cost.

Specific Aspect

Requiring a specific aspect is both very potent and rather trivial. Obviously, aspects say a lot about a character, but unless the required aspect is particularly boring—and why would you want that?—then it’s not much of a cost.

That is not to say there’s no point in requiring an aspect. Magic often has a setting component, so an aspect can reinforce elements of the fiction. Aspects can also be used to illustrate a choice in a setting with multiple flavors of magic, especially if your expectation is that all characters will have magic of some sort. In this case, aspects are less about cost and more about differentiation, which can be very robust.

A Stunt

Stunts make for a nice, obvious gateway into any system of magic, and much like different aspects might be gateways into different styles of magic, so might different stunts. For example, if you’re using a magic system that requires magic points, different stunts might represent different ways to generate those points.

Of course, since stunts can also be the outcomes of a magic system, you get the potential for some sophisticated interplay. It is entirely possible to build a “tree”-style magic system using nothing but stunts that depend on other stunts as prerequisites. Such systems are fun, but they often take a lot of bookkeeping to construct well.


Refresh is probably the most serious cost, and it carries a lot of potential meaning—specifically, what does the loss of refresh mean?

When we introduced the idea of refresh in The Dresden Files RPG, it served two purposes—it provided for characters with a wide range of power by trading freedom for that power, but it also underscored that the line between man and monster was a slim one, and that it was possible to be consumed by your power—that is, reduced to zero refresh. While there is no obligation to make zero refresh mean the exact same thing, the key is that a zero refresh represents a loss of agency. Mechanically it means the character is basically unable to do anything but what their aspects dictate.

Something implicitly part of a magic system are the different meanings loss of agency can have. It could mean character death to go to zero refresh, certainly, but it is often more interesting if it means the character is swept up in their magical nature, as such characters make great villains or foils down the road.

The catch is that while refresh as a cost should feel like the danger of the slippery slope, that’s not the reality. Dropping to zero refresh is basically a player choice to retire the character, not something that actually comes up in play. If you’re okay with that, then cool, but if you really want it to be a danger in play, then you’re going to need to find a way to make the choice come up more often.

In a system where each magical aspect reduces refresh by one but increases magic points, you might rule that a character can always choose to “sell out” one of their aspects, converting it to a magical one, thereby increasing their mana pool. Additionally, at the moment this happens, have a character’s stress track and mana pool restored to full. Now you have a reason for this to happen in play, as the character surrenders to their power to win an unwinnable fight.


One interesting option for limits on effects is to require that they are not universally available, but rather depend upon the appropriate opportunity. Opportunity may be defined in a wide variety of ways, but largely fall into one of two categories.

World opportunities are those that depend upon elements in the game setting. Spells might only be cast at certain times or places, or in response to certain events. This is a classic trope for a lot of horror fiction, where things may be called “when the stars are right.”

World opportunities tend to operate more like plot hooks than anything else, because they drive play toward those opportunities. If the dead can be revived in the Lap of Shialla, then that’s a great reason to go there. If the Dark One can only be summoned during a lunar eclipse on the Plains of Blood, then the adventure pretty much writes itself.

However, world opportunities are pretty restrictive for players—world opportunity is a very high cost of magic, and if it’s the only way to do things, then you probably need no other costs. Not to say that it’s unplayable—it can work very well in conjunction with high Lore characters—but it’s got very specific restrictions.

Alternatively, world opportunities can be used in conjunction with another magic system to transcend the usual limitations of magic—so spells that are more powerful, or otherwise impossible, might be castable under the right circumstances. Structurally, this is still pretty much just using magic as a plot hook, and that’s fine.

Gameplay opportunities are another approach entirely. In this case, something involving game rules must happen before magic is possible. This could be intentional, such as spending an action summoning power, or incidental, such as an ability that makes boosts do something unique.

Intentional opportunities tend to just be speed bumps to magic, and as such, they’re very popular as balancing mechanics. The thinking goes that if magic can be used less often, it’s okay if it’s more potent. Sadly, this approach has some hidden weaknesses. Frequency is a poor thing to rely on for balance because it’s feast or famine—it tends to mean that a caster’s player is either bored, doing nothing but gathering power, or overwhelming. If you pursue a model like this, try to find a way to make the non-casting part of casting to be fun and engaging as well. One trick is to allow “charge” to accumulate throughout more interesting action.

Alternately, magic can be a colorful expansion to the existing rules. Consider using magic to expand default outcomes. If you attack with Earth Kung Fu, then a boost might get you an aspect, but it might also knock your opponent back a zone. This can seem a little counterintuitive, if a player thinks in terms of “I want to knock him back,” but it makes much more sense when you think of it in terms of expanding normal capabilities.

There is also the matter of access opportunity, which exists more in the realm of character creation. Magic might require a magic skill or an appropriately magical aspect, as have been discussed previously.


Resources involve a more literal cost to casting spells. The classics include mana, spell points, or expendable spells, but are not limited to that. A spell might require invoking an aspect—and casting the spell rather than taking the +2 bonus—taking stress, or even taking consequences. Obviously, the price tag will impact the frequency of magic use.

Resources can also add an extra level of color to a magic system—perhaps resources aren’t always needed, but can be used to make magic more potent. Things like stress and consequences can be fun for this, representing powerful, dangerous magic. One caveat, though—try not to hook this into explicit combat magic. When it becomes a math problem of “I can take X stress to do Y stress to opponents,” then it feels a little less magical.

Resources and opportunities can overlap a bit in the area of player skills. A secondary skill roll to generate mana requires both a resource (mana) and an opportunity (the secondary skill roll). This may seem muddy, but it’s actually a good thing—tying more of the character’s elements together is a good thing.

One other obvious resource is fate points, and it’s reasonable that they fuel magic just the same way that they do aspect invocations. You might even make “mana” into a subcategory of fate points.


We’ve talked through all the things that can control the use of magic, but what can magic do once you use it? In terms of fiction and color, the range of possibilities is broad indeed, but for the moment we’re looking at the mechanical tools we have for expressing mechanical effect. Although it’s possible to create entirely new mechanics for these things, it’s best to start with the building blocks that we already have. As with limitations, there’s a core list of elements we can build from:

  • Fiat
  • Aspects
  • Skills
  • Stunts
  • Stress & Consequences
  • Extras


This is a fancy way to say “you describe something and it happens.” There are huge swaths of magic that can be covered by this. In some cases, this may be all that’s necessary, especially if the table is comfortable with it, but it’s a potential source of discomfort when expectations begin to differ. Still, there are a lot of effects that are best handled as fiat, even if they’re mechanically important—the magical effect may be a gateway to other rules.

For example, if magic allows a character to breathe underwater, that’s a fiat effect—it’s simply true. There’s no need to assign an aspect or a skill to represent it, unless some other element of the spell—like an inability to breathe out of water—comes into play. You could assign an aspect that never gets invoked or compelled, but the effect is much the same. That said, once the character is underwater, there are still other mechanical elements to engage—athletic skills, for example.

Magic with mechanically trivial fiat effects can still be insanely potent or important in a setting. Consider something like eternal youth—there aren’t a lot of mechanics involved, but it’s an effect that could drive an entire campaign. The fact that fiat effects don’t require you to think about mechanics means that you should think all the more about the non-mechanical elements.


Aspects can be a lot like fiat, but carry just a little bit more weight. If all the aspect does is reinforce the “officialness” of a fiat element, then that’s fine, but you can also hang mechanical effects off of them.

A lot of these effects can be covered with the usual rules for invocations and compels. Magic just tends to allow for greater flexibility in terms of the logic and color of aspect use, and while that may not seem like a lot on paper, it can actually be incredibly robust at the table.

That said, it’s entirely reasonable to use magic to add additional effects to an aspect invocation or compel. These additional effects may be fiat, or have specific mechanical effects. An aspect like Shadow Step might be invoked to cross many zones at once. An aspect like Armor of the Light might be invoked—and used up—in lieu of taking a consequence.

One thing to consider is whether or not the effect creates a new aspect or adds a new effect to an existing aspect. Sometimes the logic of the effect makes the answer obvious, but when in doubt, try to extend an existing aspect. Not only does this reduce aspect bloat, it strongly encourages engaging with existing aspects.


Magic can be used in lieu of skills, and in fact one of the most common simple systems of magic is to use a magic skill in place of another skill, such as throwing around bolts of force as the functional equivalent of a weapons skill. This is fine as far as it goes, but it only holds up so well as a general-purpose tool.

More interestingly, magic can be used to expand the scope of existing skills, moving them into the realm of the supernatural. These might be simple expansions of capability, such as perception skills extending awareness into the infrared or spirit realm, or they might be mechanical hooks, like “The Hammer of Terror,” altering the weapon skill so that when you generate a boost, you also inflict mental stress.


Magic can add stunts or alter existing stunts, but the most common use you’re going to see for stunts is the addition of magical stunts—stunts that have magical effects that are often more potent than normal stunts, but which are offset by costs or requirements.

The most obvious example of this is a stunt that lets you do something magical, like line-of-sight teleportation or turning into a rat, but at a cost. The cost may be as simple as the expenditure of mana points or may be something complex and ritualistic. Because stunts are such self-contained rules elements, the components of cost and balance are much closer to the surface than in other approaches, so it’s important to think about them from square one.

Stress and Consequences

An easy and obvious effect of magic is to fiddle with stress and consequences. Healing magic may recover them or protection magic may increase capacity. Just be careful that this doesn’t make magi into bulletproof juggernauts—unless that’s your intent.


Magic is a great way to get permission for an extra. Whether it’s summoning a hound of fire or calling lightning down to crackle along the length of your sword, extras can be a reasonable way to handle them.

If you do this, it’s a great illustration of how to “plug in” a magic system. The extras rules are quite robust, but they’re also very open-ended. If the entirety of the magic system was just the ability to create extras, they would quickly get out of hand, so some sort of limitations are in order. The limitations that you use should be consistent enough to feel like a coherent magic system. If you make sure that each new extra makes sense in the context of existing ones, you will find that the logic of your magic system can emerge quite organically.