A wizard was only able to use this spell to create a single homunculus at a time. If cast while the original homunculus still lived, the spell failed.
In addition to verbal and somatic components, the spell required several material components: ash, clay, and the root from a mandrake plant. It also required an expensive dagger encrusted with jewels worth at least 1,000 gp. During casting, the wizard spoke the verbal component and cut themselves with the dagger. Blood was dripped onto the ash, clay, and root. The wizard then touched the material components and if the casting was performed correctly, a homunculus was created.