There are lot of elements that go into building a fantasy world that will draw the readers in and allow them to love this new world and believe it can all be true. Strong characters are pretty much at the top of the list, but right up there are the rules of magic and how it works–or doesn’t–within that world.
For me (speaking as a reader here), I want to learn the parameters the writer has established for his/her world and then watch how the action plays out against that backdrop. The rules have to be clear and consistent. No sudden changes just to make it easier for the writer to tell the story because that’s cheating. If the rules are broken, there should be a terrible price to be paid by the character who breaks the rules. Yeah, I want him to pay with blood, pain, or even being cast out and shunned for what he did.
On the other hand, that isn’t to say that every character in a book has to have the same abilities or even the same attitudes toward magic. One of the best examples of what I am talking about here is Mercedes Lackey’s Valdemar series. Each country in her world has its own view of magic, and often it is those differing views that causes the conflict in the story. Her Heralds only believe in very specific gifts. Another country limits the use of magic to its priests. Another treats magic as a science. It all brings an incredible richness to her world.
Another favorite of mine, which was one of the very first fantasy series I ever read, is The Ozark Trilogy by Suzette Haden Elgin. (Book One is Twelve Fair Kingdoms.) The magic was amazing. There was Granny Magic, practiced by feisty, little old ladies in button top shoes. The men with magic were called wizards, and they thought they were the ones who were really in control of the world. But the great part of the story was that the real power in the world rested with a young woman named Responsible of Brightwater. You see, names have weight when it comes to women. Men’s names are simply that: men’s names. By the way, Responsible has a sister–Troublesome of Brightwater. I love that. (The author also has another sci/fi series about Coyote Jones, another great name.)
When I built my own world in the Warriors of the Mist, I had to develop my own rules. The Warriors themselves mistrust magic of all kinds. Merewen, the heroine in My Lady Mage, can mindspeak with horses. The heroine in Her Knight’s Quest is a powerful earth mage. Again, the magic plays into the conflict of the story because the Warriors need allies, but they are reluctant to trust someone who wields such powerful magic. On the other hand, the villain has no compunction about sacrificing his people for the power magic gives him.
So do you have favorite stories and favorite authors who are especially adept at making you believe in their worlds? Because, you know, that’s a special magic of its own.