Senpiamancy

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Senpiamancy is the practice of creating headmates through various techniques. A headmate created through senpiamancy is called a "senpia". The term was created as an alternative to the term tulpamancy and specifically denotes a person who believes the creation of their headmates is due to psychological reasons, whereas tulpamancy can refer to people with both metaphysical and psychological beliefs.

Related Terms
Thoughtform may be a similar term or synonym.