This is a Steve Jackson Games SJG6001  Gurps Fantasy Roleplaying game Magic System & Game World Book. It was released in 1986 (Softcover).

GURPS (Generic Universal RolePlaying System) Fantasy provides a versatile magic system and background information for a fantasy campaign world, with its first edition published in 1986. The magic system allows for various ways to cast spells, including individual casting and group rituals. The game world of Yrth, introduced in GURPS Fantasy, is a core setting for GURPS fantasy campaigns.

In the 96 pages of GURPS Fantasy, you'll find:

Official magic rules for the GURPS system, with many different ways to cast spells. Work alone, or gather a circle of powerful mages, for arcane rituals that bend nature to your will...

Yrth, a world background blending the empires and faiths of medieval Europe with the wonders of magic... where the power of sorcery rules the fate of nations!

New advantages, disadvantages, and skills.

An extensive, well-explained list of spells hundreds of them.

Advice on character creation, and how to roleplay nonhuman races, including Elves, Dragons, Vampires, and more!

Detailed rules for designing and creating individual magic items.

Complete Table of Contents, Index, and pull-out Table of Spells for easy reference.