Identify the Logic of a Magic System in a Fantasy Novel

The best magic systems are not just imaginative: they are internally consistent, they have real costs, and their rules determine what kinds of stories can be told. Brandon Sanderson's distinction between hard and soft magic systems is a useful starting point, but the real test is the consistency check: where does the system risk breaking its own rules and how does the author handle it? This analyses or designs a magic system at that level of craft.

I am reading or planning {WORK_TITLE} and want to understand the logic of its magic system (or plan one with internal consistency).

Analyse or design the magic system across:
1. **The rules**: what the magic can and cannot do, and whether those limits are established clearly in the text or implied
2. **The cost**: what using the magic requires of the user (energy, time, material component, sacrifice, training, or other), and how this cost drives narrative tension
3. **The hard versus soft distinction**: whether this is a hard magic system (rules clearly defined, allows for puzzle-style problem solving) or a soft magic system (creates wonder, rules are mysterious), and how that choice affects the story it enables
4. **The consistency check**: the most significant moment in the text where the magic system risks breaking its own rules, and whether it handles this well

Write for someone interested in speculative fiction craft, not just a reader.