With fantasy, you’re playing God. You’re creating a new world with its own laws, science and values. You’re large and in charge of everything, from the length of the day, to the length of the seasons, to the dining etiquette of your nation’s nobility. Yet, with great power comes great responsibility. To create a realistic fantasy world, you must know the common elements of fantasy and how to work with them.
Magic is in most fantasy novels. It’s fun to work with, and truly creates a whisk-you-away adventure that’s out of this world. However, you must think of magic like anything else. It is like history or language – you cannot change it as you see fit. As odd as this is going to sound, magic has a logic.
Magic must have rules and restrictions – whether it’s J.K. Rowling’s Ministry of Magic creating and enforcing its laws, or an old book on the laws of the land. You cannot just use magic when and as it suits you. There must be an underlying science to its use. Find the logic and you start to understand how the magic works.
In the Wizard of EarthSea Trilogy by Ursula K. LeGuin, the magic was based on knowing the true word for everything. Once a being’s true name was known, it could be summoned or used. The more a wizard knew the true language of the universe, the more powerful he became. The more powerful he became, the more he could engage with the forces of darkness. The more he engaged in the forces of darkness the more he learned about truth. On top of this logic, LeGuin laid a plot of a young boy plucked from his village and sent to wizard’s school where he more by accident than intent, names an evil which is then released into the world and which he then has to battle. As an aside, LeGuin claims she doesn’t mind J.K. Rowling nicking her ideas, but she wouldn’t have minded some credit being given.
George R.R. Martin was very careful with his use of magic in Game of Thrones. As a game changer, it doesn’t really make an appearance until the second book. There are laws and restrictions, ramifications on the user and the target – as there are in our society when it comes to driving or alcohol.
Moreover, if magic can create something, it must also be able to destroy it.
Think about the main ways in which you wish to present magic.
How does one harness it? Are you born with the ability and channel it like the warlord Merlin? Do you use a wand? Do you speak the spells to cast them? Is there a magical object that channels the magic, making the ability accessible for all who wield said object?
How is magic viewed? Is magic a gift or a curse? Is there segregation like that seen in Harry Potter? Remember, where there is good, there is also bad.
What are the repercussions of using magic? Can magic be used for fun and recreational purposes?
However you choose to represent magic in your book, be sure to keep it consistent. If teleportation is possible, why not teleport everywhere? If the wise old wizard gives you a potion to cure illness, what other potions does he possess (or not possess)? Magic is fun to explore and get creative with, but if you understand its boundaries and laws, you’ll understand its place in your novel.