Brandon Sanderson, a fantasy author and teacher of writing, described two core magic systems in fantasy. The first is a hard system, in which there are clear rules. The characters do x and y is the result. Magic is essentially a kind of science or engineering, even if they don't understand it that way, and it achieves basically predictable results. The second is soft, where magic works in mysterious way and no one (possibly not even the magicians, certainly not everyone else) is entirely sure what's going on to achieve it, nor necessarily quite what the outcome will be. He says some other things too, about what the effect of this in your storytelling, which are quite interesting, but not entirely relevant here. If you'd like to read more, there's a wiki link . In broad terms, something like the Dresden Files or most of Sanderson's own stories use Hard Magic because it's predictable while Lord of the Rings and Game of Thrones use soft magic because it's mys...
This blog is written with the assumption that Wizards of the Coast lose their marbles and appoint me to be the lead designer for 6e D&D! It's not going to start as a serious play-test build, more outlining the ideas I'd like to see but if there is enough interest it might build up to more.