Rule 9 of 24 · Chapter II — Systems and Their Price
Solve problems with what you've shown
Why this rule exists
The oldest broken promise in fantasy is the rescue that arrives from nowhere: a new spell, a hidden power, a convenient god, revealed at the last moment to untie a knot the story could not otherwise loosen. It feels like cheating because it is, in a precise sense, retroactive, changing the rules after the reader has already invested in the old ones. A climax satisfies when its solution was available all along, hiding in plain sight among things the reader was shown, so that the ending feels earned and even, in hindsight, inevitable. The reader's pleasure is not in being surprised by a new rule but in being surprised by a clever use of an old one.
In practice
Resolve your crises with capabilities, objects, and rules you established earlier, ideally ones the reader half-forgot. When you find yourself needing a new power to escape a corner, go back and plant it far enough upstream that its later use reads as payoff rather than rescue, and give it a cost so the escape is not free. Audit each turning point by asking whether an attentive reader, rereading, would nod at the setup or cry foul at the invention. Save your genuine surprises for character and meaning, and let the mechanics of the escape be, on reflection, fair.
When it doesn't apply
A revelation that recontextualizes what the reader already saw is not a cheat; it is a gift, provided the clues were truly present. Some stories are about being overwhelmed by forces beyond understanding, where a clean, earned solution would betray the theme. And an occasional stroke of luck is human, so long as luck rescues characters into worse trouble rather than out of it.