Most fantasy books and games don’t bother getting too deep into the details of exactly how magic works. Such things usually remain ill-defined or out of sight and I’m not here to advocate that that must change. Unless the mechanics of magic really matter to the plot or gameplay, why bother? For one thing, there’s always the risk of coming up with clunky mechanics which are worse than none at all. Afterall, in the fantasy genre, magic is accepted and is, arguably, one of the requirements for a fantasy setting (arguably because I’d still call it fantasy if you had elves, dwarves, giants, etc. and no magic). Yet, should your interests lie that way, defining your magic mechanics can be useful for you as a writer, opening up everything from useful plot twists to entire novels.
Take one example from D&D of old. While recent editions fuzz things up a bit, it used to be that wizards would store the power of their spells in their head. Preparing a spell from their spell book actually captured that spell internally, sort of writing a rune on your brain. Although the game didn’t treat it this way, it is much like the wizard was an animated staff or wand: a repository for stored, charged magical energy. What would happen if you smashed an axe into said wizard’s head? Well, aside from ending the life of the wizard, nothing much else. But interestingly, the game did allow for you to break your Staff of the Arch-Magi and simultaneously release all the stored charges as a huge, retributive strike that would generally kill the wizard and anything else around. But why didn’t the wizard explode if his head was smashed? You could construct an argument that, just like with a nuclear bomb, the precise release of the magic was required for an explosion and anything else would just cause it to fizzle (although all the non-nuclear explosives in a nuke going off is still a good-sized boom). But in reality, I think it just wasn’t really considered because there wasn’t a “theory of magic” applied to the game rules.
As a D&D player, wizards are my favorite class so I’m actually not too upset that a head wound doesn’t cause my character to explode. But from a writer’s perspective, that would open up some interesting story possibilities, wouldn’t it? What would it mean to your fantasy novel if magic involved the containing within yourself of huge, dangerous energies? With such energy you could cast powerful spells of creation and destruction but if you lose control of it: boom, you explode. That, of course, may not fit your conception of magic at all. As with me the D&D player, many readers and writers may not want their grizzled wizard or lovely sorceress to explode. But there are other mechanics for magic, each with their own possibilities for shaping stories.
Let’s turn to a basic model of magic mechanics. For those of you experienced with the corporate world, we’ll trot out the hoary Quadrant Graph, so beloved of HR and management consultants :). Here, let’s model magic mechanics on two axes. On one axis we have whether magical energy is channeled from an external source (aether or the like) or stored (like in a wand, staff, potion, scroll, wizard’s brain). On the other axis we have whether the magic power is external or internal to the magic-user.
Internal/Stored: this is the D&D wizard model which was based on an early fantasy novel (I forget the name and author). Here the magic exists as energy stored within the wizard’s body, ready for release with the appropriate verbal and/or somatic components. What can you do with this in a story? Well, aside from having a wizard’s head explode (and I’m not being entirely silly, in the right story that could be quite a nice surprise for the reader), it can have all sorts of interesting side effects. Personally, I don’t like the idea of magic corrupting my casters (sort of like Sith corruption in Star Wars) but you could certainly imagine wizards who store this much power within themselves might become twisted, misshapen or otherwise changed. You could also have the magical energy be stored in scars, blood (which could be removed from the wizard to make a potion), lumps, enlarged skull, etc. Finally, it opens up the possibility of magic objects being incorporated into the wizard’s body to allow the storing and control of still greater power: gems embedded in the flesh or skull, piercings, tattoos, etc. The aesthetic of this type of magic may or may not appeal to you (it doesn’t to me to be honest) but much can be done with it.
External/Stored: in D&D, there is a host of magic of this sort from fairly common potions and scrolls to wands, staves, magic swords & shields, rings, horseshoes, bags, just about anything really. Here the creator of the item infuses an object with magical energy. It is both a container of the energy and the mechanism for releasing the energy. This is very familiar in fiction and gaming, from the rings in Lord of the Rings to the tier gear of your typical MMO.
Internal/Channeled: In this case the magic passes through the magic-user but it is not stored energy that is being tapped, instead the magic-user taps some external source of energy, aether, the Force, whatever you want to call it. For any given use of magic, it might look a lot like Internal/Stored in the sense that someone watching might see the same verbal and somatic components: magic words and flicks of the finger. But typically in games and stories, the amount of magic a user can tap is different: rather than being determined by the number of spells the wizard prepared (stored in himself), the user is only limited by fatigue: it gets tiring to draw that energy from the air and after a while, you need a break. This is the mechanics behind many MMO casters but also some games and books that require “mana”. The only distinction in this model is that the energy physical passes through the user’s body. Aside from the Aesthetics of the energy coursing through the body and out the fingers or eyes (or what have you), it may not make a whole lot of difference. However, as with the internal/stored, this amount of energy passing through the user might change the user’s body, like the corruption that dark side Force users experience in Star Wars. And as before, there might be gems, jewelry and other objects that the user can incorporate into their body to help them cast magic.
External/Channeled: this is much like internal/channeled except that the energy does not pass through the user or an object. The user or object sets up the circumstances that causes the energy in the aether or force to do something. Maybe the user creates an external ‘tap’ that then creates a tear into the aether from which the magic power flows. In Star Wars terms, perhaps this is a good user of the Force. In RPG terms, this is often what a holy caster does: they tap the magic energy of their god when they cast a spell.
This quadrant representation is just a model, meaning, it is just one way to look at the situation. One can easily blur the lines or cut things a different way. As with any model, you may find it useful, or you may not. If it doesn’t help you with your project then by all means, ignore it. Also, as should be clear from my heavy use of D&D examples, nothing says you just have to use only one quadrant either. D&D pretty much uses all four quadrants and so can your book, although your book many not need that much complexity. That is, establishing and explaining the four varieties of magic might not be worth the trouble.
So what to do with this as a writer? One answer is nothing at all: a theory of magic is not required for a great fantasy book. If none of this interests you, don’t bother with it. But if it does intrigue you, it can serve a range of purposes.
At one end, a theory of magic can remain entirely behind the scenes but by having an idea of how magic works in your world, it can help you keep the use of magic consistent. Just as it is good for a writer to have a consistent voice within a work, it is good for magic to have a consistent feel within a work. If you have a clear idea of the magic mechanics in your story, then you are more likely to give magic a consistent expression.
But there is a lot more you can do with it. As an example, if you go with the stored/internal model you can have it affect the plot at some point: the evil caster explodes when killed, the good caster worries about containing her magic and possibly harming others. Or the quest for a gem to provide an internal repository for storing magic might drive a plot thread. Perhaps the nature of magic itself drives the main plot.
Myself, I do like to toss around these ideas. One of my stories is about the nature of spirits and the power they grant. The main plot pertains to what the protagonist will do for love but the mechanics of spirits, gods, magic, life and death drive almost everything to do with the story. In my current story, magic is channeled from the ley. Archons used this magic to float their domains and castles, dragons channel ley with their wings to fly. The whole story revolves around what happens when the floating islands start crashing back to Earth after the Archons disappear (and threaten to return 🙂 ). For me, the magic mechanics infuse the story and provide much that I want to write about, at least in these cases. In other stories, it takes more of a back seat: it’s part of the setting but not explained nor do the mechanics drive the story.