What makes a good magic system in Games? How do you make Magic fun to use?
Most important part is to make the magic spells hit really hard and wide. I'm talking about colossal sized spells. Let me feel the impact and inflict absolute mayhem. No tiny fireballs that are a glorified reskin of bow attacks. Dragon's Dogma did it right.
Not making it menu navigation. In other words, every game fails at it.