Spend enough time in writing circles—especially fantasy and science fiction ones—and you’ll hear it sooner or later: your magic system needs rules. Usually this advice is framed around “hard magic systems,” where every power has limits, costs, and clearly defined mechanics. And look, I love rules. Rules can create tension, fairness, and satisfying problem-solving. But I think the conversation often slips into something more rigid than it needs to be—something that risks draining the magic out of, well… magic.
Because here’s the thing: if you write the rules too tightly, what you’re really building isn’t magic at all. It’s science. Yes, fake science—but still a system that behaves like engineering. Inputs, outputs, conservation laws. There’s nothing inherently wrong with that, but mystery is part of what makes magic feel magical. Strip all of that away and you’re left with a technical manual in wizard robes.
More importantly, rules should serve the story—not the other way around. Rulebooks are not especially exciting to read. (Be honest: have you ever read the Monopoly rules cover to cover for fun?) Stories thrive on emotion, tension, and surprise, not on perfect system compliance. When the narrative starts bending around the magic system instead of the magic system flexing to support the narrative, something has gone wrong.
Movies offer a useful comparison. We know a hero’s gun must eventually run out of ammo. But do we count the bullets? Usually not. We simply accept that, at the worst possible moment, the last shot is fired and the click follows. That’s not a plot hole—it’s a beat. It’s storytelling. And it works because it heightens tension exactly when the story needs it to.
Magic can—and should—work the same way. If the system is foregrounded, then yes, it needs internal consistency. If readers are meant to engage with the mechanics, to anticipate outcomes, to worry that the hero is about to walk into danger with an empty magical revolver, then the rules must hold. In those cases, readers counting the magic bullets can actually be a feature, not a bug. The tension comes from knowing more than the character does.
But that doesn’t mean every spell needs a spreadsheet. If magic exists in the background—if it can’t be used to meaningfully solve the plot’s core problems—then its rules don’t need to be defined at all. At that point, it’s scene work. Texture. Atmosphere. Like the ornate turrets on a castle you describe to set a mood, not because anyone is going to fire artillery from them later.
So yes, have rules. Love rules. Just don’t worship them. Magic systems aren’t there to prove how clever we are as designers. They’re there to serve character, tension, and story. And sometimes, leaving a little unexplained is exactly what keeps the magic alive.
