I've never done a post on magic systems. The closest I've gotten to it is my post on writing magical items. One of the reasons I haven't approached magic systems is because others have done a much better job talking about them than I can, and to be honest, I haven't studied them that much. But my work-in-progress does have some magic systems in it, even though I don't always think of them as magic systems, and so today I'm bringing you the source that I use when I need help with magic in my story--and really, it's such a good resource that it deserves its own post on my blog.
Brandon Sanderson is one of the top-selling fantasy writers today, and what's even cooler is that he understands and is conscious of what does in his writing and can teach it well to others.