From publisher blurb: This title contains six spells related to studying, altering, and creating creatures. They are formatted so as to be compatible with any games using the sorts of basic fantasy role-playing game rules developed starting in the 1970s. They can be used as-is with games like Goblinoid Games’ Labyrinth Lord and Mutant Future and can be easily modified and expanded for use with successor systems like OGL or other games altogether.