Readers forgive a lot in a fantasy novel, but they do not forgive a magic system that bends to suit the plot. If a wizard solves a problem with a spell that was never mentioned, it feels like cheating. If the same wizard cannot solve an easier problem for no reason, it feels arbitrary. A magic system that works gives your characters real limits and real costs, and those limits are what create the story. This guide explains the idea of hard and soft magic, the four questions that define a system (what it does, what it costs, what limits it, who can use it), how to test your system against your plot, and how to record it. The last section shows where to keep the rules in Quillen.
The short answer
Define your magic by its limits, not its powers. Decide what it can do, what it costs, what it cannot do and who can use it, and write the rules down. Then make sure your plot is solved by characters who understand the rules, not by new powers introduced when needed. In Quillen, the World category has a prompt for exactly this ("Magic and magicians: rules of magic, magic and technology"), where you can keep the rules next to the rest of your world.
Hard magic and soft magic
Writers often describe magic systems on a spectrum. A hard system has clear rules that the reader understands, so magic can be used to solve problems because the reader knows what it can do. A soft system keeps its workings mysterious, so magic evokes wonder rather than solving plot problems. Neither is better. They do different jobs:
| Hard magic | Soft magic | |
|---|---|---|
| Reader's understanding | Knows the rules | Senses the wonder |
| Best for | Plots solved by clever use of the rules | Atmosphere, awe, mystery |
| Risk | Over-explaining, and rules lawyering | Feeling arbitrary, or an easy way out |
| Rule of thumb | Characters may use magic to solve problems | Magic should create problems, not solve them |
Most fantasy sits in between. The key principle is that the amount of problem-solving a magic can do should match how well the reader understands it. The less the reader knows about how magic works, the less it should be able to save the day.
Four questions that define a system
1. What does it do?
Describe the effect in the simplest terms. "Binds a current for one crossing" is clearer than "controls water". A narrow power is more usable than a broad one.
2. What does it cost?
Cost is the engine of drama. It might be energy, health, memory, years of life, a favour owed or a resource that can run out. A magic with no cost has no stakes. The best costs are the ones that hurt the character at the worst moment.
3. What are its limits?
Limits keep magic from solving everything. A spell may only work on moving water, only at night, only on things the caster can see, or only once. Limits also create ingenuity: characters have to be clever within them.
4. Who can use it, and how do they learn?
Is magic inborn or taught? Rare or common? Respected or feared? The answers define the society around it: guilds, secrecy, persecution, inheritance.
A worked example
In Hollow Crown, ferry-charms are the magic system. Answering the four questions:
| Question | Answer |
|---|---|
| What does it do? | Binds a current for one crossing |
| What does it cost? | Each charm drowns one memory of the person who casts it |
| What are its limits? | Only works on moving water; lasts one crossing |
| Who can use it? | Ferrymen who learn the old night channels; others cannot |
Look at what this gives the author. Wren can use a charm to cross a flooded valley, but she pays with a memory, and she cannot use one on a still lake. The system creates tension: the more she uses it, the more she loses of herself. It also generates plot: a rival ferryman who has used too many charms no longer remembers why he started.
Test your system against your plot
Before you finish a draft, run three tests:
- The solution test. For each big plot problem, check how it is solved. If magic solves it, were the rules established earlier? If a rule is introduced at the moment of need, move it earlier.
- The cost test. Does every use cost something the reader can feel? If characters use magic freely with no consequence, readers stop caring.
- The limit test. Could a clever character use magic to solve the entire plot in one move? If so, add a limit, or explain why they do not.
Technology and magic
If your world has technology as well as magic, ask how they interact. Why do people still walk if magic can fly? Why do they still farm if magic can feed? The answer is usually cost or scarcity, and it shapes the whole society. Do not leave this unanswered: readers will ask.
Common mistakes
| Mistake | Problem | Fix |
|---|---|---|
| Magic with no cost | No stakes | Give every use a price that hurts |
| A new power appears when needed | Feels like cheating | Establish rules before the climax |
| Magic that solves everything | Plot collapses | Add limits |
| Explaining the system at length early on | Slow opening | Show the system through use |
| Not writing the rules down | Inconsistency across chapters or books | Record rules, costs and limits |
| Ignoring the social effect | A world that does not feel changed by magic | Ask who has it, who fears it, who profits |
Do it in Quillen
Quillen's Lore section has a prompt for magic in the World category, so you can keep the rules beside the rest of your worldbuilding.
- Open Lore from the left sidebar, then open the World category and click New Entry.
- Name the entry, for example "Ferry-charms" or the name of the region the magic belongs to.
- Click the card titled Magic and magicians (rules of magic, magic and technology). Write the four answers: what it does, what it costs, its limits and who can use it.
- Use The world and Social organization to note how magic affects society, and Daily life for how ordinary people live with it.
- Link it to your plot. In your Outline, open a card where magic is used and use the Notes box to refer to the rule, so you can check the scene against it. See how to write beat cards.
- Keep it current. When you discover a new rule while drafting, write it into the entry straight away.
Checklist
- What the magic does, in one plain sentence.
- A cost that hurts at the worst moment.
- Limits that stop it solving everything.
- Who can use it, and how they learn.
- Every use in the plot checked against the rules.
- Rules written down, and updated when they change.
Common questions
What is the difference between hard and soft magic?
Hard magic has clear rules the reader understands, so it can solve problems. Soft magic stays mysterious and evokes wonder. The less the reader understands the magic, the less it should be able to save the day.
What should a magic system define?
What it does, what it costs, what its limits are, and who can use it and how they learn.
Why does magic need a cost?
Cost creates stakes. Magic with no price has no tension, so make each use cost something that hurts at the worst moment.
How do I test my magic system?
Check that rules are set up before they solve problems, that every use has a cost the reader can feel, and that no clever character could solve the whole plot in one move.
Where do I keep magic rules in Quillen?
In the World category of Lore, which has a 'Magic and magicians' prompt for rules of magic and how it interacts with technology.