From the back of the book:
In traditional legends, magic has always been a force that granted great power, but which carried risk in its use. For those who appreciate this uncertainty and desire to let magic be something mystical and untameable, something more than just an entry on the spells per day table, Natural 20 Press and Mystic Eye Games present Wild Spellcraft.
Wild Spellcraft provides game masters with a toolkit for including the unpredictable forces of magic in their game with whatever septh and complexity they want. Ranging from rules for spells gone awry to prestige classes for those who try to master magic in its rawest, most chaotic form, Wild Spellcraft is designed to be modular, to f [sic] it into your game in individual pieces or in its entirety.