Magic is an essential component of any fantasy story. Witches and wizards, elves, dragons, curses, enchanted objects, they all have their place in the genre. The amount and types of magic in a story, and how it’s introduced to the reader, can make the difference between an enthralling tale of wonder and a collection of unreadable pages filled with mangled Latin and tired tropes.
So what’s the best way to write magic? Simple. Start small. Keep it subtle and mysterious at first. Build your reader’s expectations so that when your powerful wizard appears, they know something important must be right around the corner. Too many stories are drowning in magic from the first paragraph, with all-powerful beings and mystical creatures bumping into the protagonist at every turn. Perhaps the protagonist is one of these beings. A good fantasy writer layers their magical system with diverse elements that unfold accordingly as the plot and characters develop.
This brings up another point. Why have magic in the first place? What does your character need to accomplish that only magic can do? Does it really make the story more interesting to have a dragon swoop down on your adventurer mid-quest, or are you just trying to spice up an otherwise uninteresting scene devoid of meaningful events? Do the dark powers your villain possesses actually contribute anything to their character, or to the plot? Too often, magic is a shortcut, a way to resolve scenarios without decisions that would require any actual character development on the part of the writer.
Finally, and I can’t stress this enough, make sure your magic has consequences. Magic is power, in one form or another, and power affects those around it. Characters who use or experience magic shouldn’t do so without it having an impact on them. They should feel the results of their actions. Casually slinging spells about to have a character solve day-to-day problems might seem appealing to anyone who grew up reading Harry Potter and wishing for their own letter from Hogwarts, but it’s hard to do well, and even harder to bring across in an original enough way to hold a reader’s interest without any underlying sense of purpose or impact.
As a First Reader, I’ve rejected many fantasy submissions with strong premises because the author portrayed magic badly. It was too easy, too prevalent, and in many cases completely unnecessary. As a writer, do everything you can to keep its use relevant, and to hone your magical system down to its simplest and most effective form before you send off that latest submission. Your fantasy writing will suffer if you don’t.