From the introduction:
As a fantasy game, magic surrounds and fills the lives of characters in Grey Lotus. It is a constant source of mystery for the characters, yet it aids them almost daily. Despite this, the rules and spells given in the Rulebook were only the most basic, due to space limitations. This supplement expands and clarifies on the rules. It covers all things from advanced magical skills, to new spells, to new Disciplines for characters, and even details the powerful magics of the Kurr’d-ah and the forbidden powers of the Magi. This is the ultimate reference for players of magician characters.
In addition to provide extended options for magic, this supplement also provides several revisions and clarifications to the rules presented in the core book.