dollyt8
Troubadour
Jed Herne is a fantasy author and YouTuber who I highly recommend in general. He's got some fantastic advice for things like how to write better villains, how to make your characters more likable, how to worldbuild effectively in your novels, etc. This particular resource is a free list of potential limitations your magic system could have. I understand not everyone will be interested in that sort of thing, but for me personally, it makes magic systems way more interesting if there are some limitations and consequences involved, and there were a bunch of options that I never would have considered! I hope it's useful: Magic System Limitations, Weakness, and Consequences Guide – Jed Herne