Make power cost something

Why this rule exists

Magic and miraculous technology are only interesting when they are expensive, because a power with no price is just a plot solvent that dissolves every difficulty on contact. The moment a character can heal any wound, win any fight, or cross any distance for free, tension leaks out of the whole story, since the reader learns there is nothing here that cannot simply be waved away. A cost, whether paid in blood, years, sanity, love, or something rarer, turns power into a choice, and choices are where drama lives. The best invented systems make their users weigh what they will spend, so that every act of power is also an act of character, telling us what a person is willing to give up and what they are not.

In practice

For every ability in your world, decide what it takes out of the user, and make that price real enough to hurt. Costs can be physical (exhaustion, injury, shortened life), material (rare fuel, ruined tools), social (feared, hunted, indebted), or moral (each use erodes something you did not want to lose). Escalate the cost with the effect, so that saving a city should cost far more than lighting a candle, and let characters sometimes refuse to pay. Show the bill being settled on the page, not just named in the appendix, because a cost the reader watches land is worth ten a footnote merely claims. When a scene feels too easy, you have almost certainly underpriced the power in it.

When it doesn't apply

Not every system needs a visible cost at the point of use; some pay their price in scarcity, in strict rules, or in who is allowed to wield them at all. Whimsical or comic worlds may run on cheerfully free magic, because their stakes live elsewhere. The rule is that power must be constrained somehow, and cost is simply the most reliable constraint.

Related rules in this book

Sources

• On Fairy-Stories — Tolkien, J.R.R. Lecture 1939, in 'Tree and Leaf', 1964 — the source of 'secondary belief' and the inner consistency of reality that makes an invented world convincing.
• The Language of the Night — Le Guin, Ursula K. Putnam, 1979 — essays including 'From Elfland to Poughkeepsie' on how style, restraint, and voice make an imagined world feel true.