I think it'd be interesting to have some sort of easily learned but highly unpredictable magic, centered around cards/dice with effects based on drawn cards or dice sides. A set of dice could potentially do anything from spray water everywhere like a mystic garden hose, or suddenly burst into flames, with the overall power and risk of throwing determined by skill level (e.g a beginner throws dice and gets a small flame, while an expert throws and a large (intentionally vague) radius is set ablaze.