Hard magic systems (like Sanderson-style rules) work great in novels where one author controls everything. But in collaborative RP, overly rigid systems create arguments about whether a spell "should" work.
The best RP magic systems I have seen share three traits:
1. Clear costs: Magic costs something — energy, materials, time, sanity, lifespan. The cost prevents power creep without needing a rulebook.
2. Flexible application: Instead of spell lists, define what magic CAN do (heal, destroy, transform) and what it CANNOT do (resurrect, time travel, mind control). Let players improvise within those boundaries.
3. Social consequences: How does the world react to magic users? Fear, reverence, regulation, exploitation? This gives every mage character built-in social tension.
What magic systems have worked well in your RP settings? What makes them collaborative-friendly?