The Compleat Spell Caster is a supplement intended to add new material to the magic systems existing in fantasy roleplaying games.
[1] The book offered variant classes for magic-users, such as mystics, necromancers, sorcerers and witches.
[2]: 186 Craig Sheeley reviewed The Compleat Spell Caster in Space Gamer No.
[1] Sheeley commented that "Unfortunately, The Compleat Spell Caster won't much help people playing Chivalry & Sorcery, and would only add confusion to AD&D.
Only a game with a small magic system would benefit.