From the back of the book:
The secrets of the spirit world unveiled for the first time!
There is a world unseen by mortals, a world filled with invisible beings that whisper words unheard by all - all but the shaman. The shaman alone knows how to listen for the spirits, and the shaman alone knows their secrets.
This 96-page AD&D game accessory introduces three new priest classes with unique powers and exciting potential. More subtle and versatile than clerics and wizards, the shamans tap the energies of the mysterious spirit world, using their extraordinary abilities to further their personal goals, as well as the agendas of their unseen spirit patrons.
Shaman offers complete information on the new classes, tips for incorporating them into established campaigns, new skills, new spells, and a detailed look at the unseen world of spirits.