From publisher blurb:
The Book of Fools is a 74 page D20 book of prestige classes for the Mysaniti Campaign world. All of these prestige classes can readily be converted to fit into almost any campaign world. Twenty prestige classes are found in the Book of Fools, with lots of crunchy bits to make them extra chewy. Come and visit the machinations of the Body Thief upon your players, or maybe you aspire to be a Noble Duelist. Is the fiendish whispering of the Demonic Counselor more to your liking? In any case, come on out and enjoy. There's a prestige class for almost every fantasy gaming occasion.
The Book of Fools includes several pages discussing some new magical items, new deities & domains, and a new category of feats. The Sorcerous Ancestry feats will ensure your sorcerer learns to use his bloodline to power new abilities.