How to Write a Rule-Based Magic System

I'm known for writing very rule-based magic systems, it's kind of what Mistborn is. You have to know the rules because your readers will have figured out the rules that you've laid out for them. What I gain, why I write this way is I gain the ability to use magic to solve problems so I can make the heroes clever. In other words, I give them a set of tools and then I show you how clever they are by having them manipulate those tools in ways you did not expect. That's what I love to do.