The title pretty much says it! I’d like to explore that idea a little and would love to hear y’all’s recommendations. This thought was originally inspired by lord of the rings, but I’m also currently on a little nostalgia trip by reading The Sea of Trolls and the soft magic system in that is pretty fun
Honestly Throne of Glass by Sarah J. Maas fits. It’s more a medium magic system, if that makes sense. Instead of not clearly defined rules it more just has ever changing, very simplified, rules.