Quote Originally Posted by JoeJ View Post
Hero System and Mutants & Masterminds both have you build superpowers that can easily be spells. In GURPS you can build spells as Advantages instead of using the default magic system.
Fantasy Hero (Hero System) has specific tools for building a magic system.

I designed a magic system for a bard, whose goal was to inspire troops (or the party), by singing the night before the battle or adventure. All his spells had the following characteristics:
Area effect (affects anybody in range of his voice)
Increased duration (lasts 24 hours)
Concentration (he can't be interrupted while singing)
Extra Time (5 minutes to sing the song)
Focus (requires a musical instrument)
Gestures (his hands are busy playing)
Incantation (he must sing)
Requires a skill roll (he must sing well)
Recipient must be able to hear

It also specifically disallowed shape-changing powers, energy beams, direct attacks, or other abilities that don't fit the "inspiration" theme.

The system made it easy to design a magic system just for that kind of bardic spell.