From the back of the book:
Feel the Power!
Fantasy settings are defined by their magic . . . so different worlds need different magic systems. GURPS Thaumatology has GURPS Fourth Edition updates of the best Third Edition magic variants, plus many all-new options. This mighty tome includes:
Minor tweaks for the spell-based magic of the Basic Set: restructuring prerequisites and colleges, modifying Magery and mana, new magical energy sources, adapting spells on the fly, and more.
Radical revisions of spell-based magic, including detailed versions of the clerical and ritual magic options hinted at in the Basic Set, and the return of that Third Edition classic, "unlimited mana."
Traditional alternatives to spells, such as ceremonial, spirit-mediated, and runic magic.
World-shaking freeform magic.
Magic as inherent powers.
An in-depth look at material magic, with new alchemy, herbalism, and enchantment options; rules for free-willed items and magical gadgets; and guidelines for "the stuff of raw magic."
Notes on adapting real-world occult concepts such as the Laws of Magic, astrology, and traditional material components to any magic system.
Guidelines for running magic-oriented games, advice on combining magic systems, and detailed outlines for four distinctly different fantastic campaigns.
GURPS Thaumatology requires the GURPS Basic Set, Fourth Edition. GURPS Magic is recommended but not required. The discussions of different magical styles would enhance any game that features magic.