Way back in 2019 when I wrote about building magic systems I covered the basic needs to create a magic system. Those basic needs included the rules, the limits, and the costs. Today I want to revisit that and focus more specifically on an aspect of limits within magic systems that quite literally can make or break your story: what can magic do and what can it not do?
Although it’s easy to say magic can do anything, that in itself breaks the story. If magic can do anything, why isn’t x problem solved with magic? A famous example of this: why didn’t Gandalf call on the eagles to fly them to Mordor? Although there’s been more than a few fan theories put forward to solve that question, apply that same question to your own story. What stops someone from using a potion, spell, charm or other magic fix to calm your antagonist and thereby stop whatever catastrophe they’re causing?
Aside from the ethical questions such a fix could raise—what sort of behavior would constitute enchanting your villain to be arguably good?—large plot holes are rarely a good way to gain a reader’s trust. Even if you have a fix for such a plot hole in book two, if your readers don’t trust your ability to tell a good story they may not read to the end of book one.
Hence, even if magic can do anything, having a limitation that makes such a solution difficult if not impossible gives your story a structure to work around. That same structure gives your readers something to trust in.
Now that you know why it’s so important for a magic system to have limits, there are any number of ways you can limit it. The simplest way to impose a limit may lay in the cost of performing magic: the more complicated or powerful a magic, the more it costs.
Another way to limit magic is in the affects it can have. This can again come back on the cost and why someone might or might not want to use magic—breaking your bones just to sweep the house would certainly deter most people. Alternately, the way the magic is used might determine the reaction your magic has. Much like technology, magic can potentially have many uses.
Healing. Although it might be nice to just heal every broken bone, consider what happens when you heal a bone broken too close to the growth plate on a child: does that bone then continue growing passed when it should, or does it stop early? Is it possible that your magic is simply so slow acting that it’s rarely worth the extra week or two a person might gain from healing a broken bone? That’s all without getting into more complicated medical circumstances such as appendectomies or cataract surgery. Ask yourself what can your magic heal? What can’t it heal and why can’t it heal those things?
Weapons and warfare. Whether you’re dealing with spells flung at approaching armies or enchanted swords, magical warfare is a staple of fantasy. That doesn’t just cover offensive uses such as projectiles or explosions, it also covers defense such as shields. In this case, large spells are a good one to look at. Newton’s third law covers why: every action has an equal and opposite reaction. If blasting the approaching army with a fireball rains down miniscule embers on your army, you might be a little more inclined to avoid fire spells and opt for the standard rain of arrows from your archers.
Construction and crafting. Admittedly, these two are very different disciplines, but they amount to the same thing: creating something new with magic. Although your artisans and your masons are going to use them for very different purposes, the two have a lot in common. This is a good place to examine what kind of physical materials magic uses, or what it would take to create something entirely new from just magic. This is another place that cost can factor in heavily. If it’s possible to create a wooden beam from magic, why can’t one magic user create an entire house? Another big factor for limiting magic in this category is how it physically works. If your artisan can create an endless bucket of water, why couldn’t he do the same thing for grain or another food stuff? While water could easily be pulled from a water table belowground, it’s much harder to pull grain from a silo without eventually having to refill that same silo. Look at how your magic would have to physically work to achieve the desired outcome.
Communication. Although it might be possible to instantly send a message to someone, how do you know where to send it? Can messages be accidentally sent to the wrong person or place the way modern postal systems sometimes can? Using magic for communication opens a lot of fun possibilities such as magical video calls, but limiting it adds plenty of option for conflict, drama and a whole host of other things. Imagine if Sirius Black had accidentally gotten the wrong fireplace in The Goblet of Fire and been found by the Ministry of Magic! Much like construction and crafting, the limits in communication are ones imposed by how the magic physically works. Smashing your phone today might cause it to stop receiving calls and things—if your magic communication requires crystals to work, what happens when one of those crystals is similarly broken?
Transportation. Another big one for cost: what stops your characters from using instant transport anywhere and everywhere? Or is it a case of speed and physics that prevents instant transport from succeeding? After all, travel usually takes time which is directly correlated to how fast you move. Car accidents are a good example of what happens when you move too fast and strike a solid another object. Alternately, it’s possible that the energy cost is the big factor here. If you have to take the immediate cost of moving that far all at once, it might very well be too expensive for most people to bother with. They may be tired either way—but at least when they have to walk six miles, they can stop and rest halfway through to regain some energy.
Cooking and house care. Although a relatively minor thing to use magic for, ask yourself why someone might want to do it by hand instead of the ‘easier and faster’ magic way. Does watering the flowers cause the humidity in the house too rise too much? Or is it possible that magic is affected by heat, resulting in unpredictable enchantments? This is again another place to look at the consequences of a situation. That whirlwind summoned to get the dust off the floors won’t just get the floors—it might take the pictures off the wall and any important documents off the desk.
Animals and animal handling. For the sake of keeping everything relatively short and contained, I’m including magical animals here. Going back to the Giant Eagles—how much do they need to eat to carry that big of a party that far? A giant dragon sounds like a ton of fun, until you realize the two cows a day come out the other end. Some parts of caring for and handling animals magically falls under house care, but other parts might affect your magic user’s psyche. Prime example of this one: Eragon. As a result of using magic to hunt, he ends up going largely vegetarian.
Arts and performance. If you’ve ever done any sort of performing on stage, you know that some performances are simply magical even with the most basic of technology. A large part of that is because of the sheer amount of skill, training and outright passion put into those performances. This in itself is a good limit for magic: anyone can use it, certainly, but the amount of training and effort required to use it skillfully for large productions makes it unreasonable for most applications. Not much point in using it to paint with when it results in an ongoing energy drain. As with other categories however, reactions are also something to consider. Pyrotechnics lend a degree of amazement to any performance—but safety requirements can entirely prevent them from being used in certain spaces.
What are some of the limits of your systems? Let me know in the comments below!