Magic is one of the signature features of fantasy writing. It’s what separates it from other genres. It’s also one of the great joys of writing fantasy.
Magic allows us to bend reality. It should come as no surprise that the words witch and wicker share an origin. Wicker is bent wood furniture, a witch bends reality itself, shapes it.
Magic means our characters can do amazing things. They can bend the laws of nature. They can overcome incredible obstacles.
Is there anything that magic can’t do? Personally, I have only two rules for creating magical systems. Here they are:
Magic must be consistent
Magic can bend the laws of nature, but it must have it’s own set of rules. Fantasy readers are willing to suspend disbelief on many, many aspects of the world they are reading about. But they will only go so far. Walter C. Langer once said “People will believe a big lie sooner than a little one.” I don’t know much else about the man, but that one quote is a doozy.
Fantasy readers will suspend disbelief on the laws of physics, if you demand it. They will believe that magic exist. They want to believe it, even. They will believe your character can do incredible things.
But the little lies, the tiny discrepancies between one scene and the next, will break the spell. If you say the druid needs nature to cast a spell, and three chapters later they cast a spell in town, you will get angry emails from readers, guaranteed.
In short, there must be rules for how magic works, what it can do and what it can not. Those rules are the big lies that make your world believable to your readers. A lack of rules, or a discrepancy in the rules, is the small lie that will break the suspension of disbelief.
Magic must not be overpowered
My son is a big gamer, both online MMORPG (Massive Multiplayer Online Role Playing Game, think Warcraft) and Pathfinders. The jargon of gaming gets thrown around our house a lot. “That’s so OP,” he will declare. OP – over powered, refers to a character or ability that is so much stronger than the rest of the game that it negatively affects game play.
Stories require tension. As cool and exciting as Magic can be, it can be a tension killer, too. If you character can overcome any obstacle with magic, where’s the tension? How do you keep the reader on the edge of their seat? How do you keep them from thinking, oh, she’ll just use spell x and problem solved?
Why do you think so many of the great epic fantasy series aren’t told from the point of view of the wizard? Lord of the Rings would be a very different sort of story from Gandalf’s point of view. How would the Belgariad have read if the wizard Belgarath had been the main character? Magic might be exciting but often less powerful characters make a more interesting story.
Comic book superheroes are often OP as well. The comic book solution has traditionally been to pit the hero against a super villain. If you must write the powerful mage as your main character, you must also give them equally powerful obstacles and enemies.
I love writing magic. It’s fun. It’s allows us to explore levels of reality and outcomes that wouldn’t otherwise be possible. Just keep it consistent and make sure your story still has tension.