GURPS Thaumatology: Ritual Path Magic offers a powerful free-form magic system that has garnered much acclaim since its introduction. The catch? There's a lot to learn for everyone – and a lot of judgment calls to make for the GM.
How to Be a GURPS GM: Ritual Path Magic is here to lend a hand. It offers tips and tricks, points out pitfalls, and provides new mechanics to handle troublesome situations. It also comes with two bonuses: a quick-start system (Ritual Path Magic Ultra-Lite) and a fistful of worked example spells that you can use right away.
You don't want to stay an apprentice forever, do you?