4. Every sentence must do one of two things – reveal character or advance the action.
Every sentence. Not just chapter or scene or whatever. I’ll go one further and say every letter must advance or reveal. OK, not really.
Vonnegut's 4th rule is nonsense, in my view. How many great books can you name that don't follow this? A lot.
I'd like to challenge that, but will accept the quibble that no books are perfect.
How many books are there that actually follow this? I'd think they are firmly in the minority. Is there a single fantasy example that could be said to adhere faithfully to this rule?
In any event, I think it is a misguided way to approach books as an overarching art form. Certainly, you can write a book in that manner if you wish. But there is no reason an author should feel compelled to limit her writing to that style.
Maybe we are taking two different ideas from what he is saying because even reading the first few paragraphs of Twilight, though not regarded as a well-written series, does in fact adhere to this.
Folks all make good observations here, but I'm not sure they speak directly to the original question. The comments are all about what makes a story interesting. Any story. The question was: what makes a fantasy story interesting.
The easy answer is: the fantastical.
There is no real answer to this question because all readers are different and find different things interesting. The best you can do as a writer is write what you find interesting and try to attract those readers to your work who are also interested in the same things.
One important point in my opinion is the interaction between the characters and the fantastical elements.
Folks all make good observations here, but I'm not sure they speak directly to the original question. The comments are all about what makes a story interesting. Any story. The question was: what makes a fantasy story interesting.