This lecture explores the connection between Tantra and the magic tradition of Nilācala in Assam in order to explain the encounter between Brahmanism and magic. First, the doctrinal, ritual, and mythical background of the cult of the Goddess Kāmākhyā, whose roots go back to the esoteric sexual path of Kaula Tantra praxis will be discussed. Having traced the history to this path, which around the 10th century switched from blood sacrifice to a mystic-erotic ritual centred on the yoni-pūjā (worship of the vulva), homologizing blood offerings and erotic rituals focusing on the human body as a source of sexual fluids necessary to obtain such supernatural accomplishments (siddhis), this lecture then examines the concept of siddhi as a ‘magical power’ that can be acquired only by those belonging to the kula (clan), the only ones who know the yoni’s secret (the restricted transmission of siddhis over kula’s generations being a complement to the ideology of blood sacrifice). Finally, it considers the intersection of indigenous traditions and Brahmanical ritual praxis in Assam as the source of the peculiar cult of the yoni of Kāmākhyā. From this discussion, Assamese Tantra emerges as a religious phenomenon that crosses socio-cultural boundaries and encompasses apparently irreconcilable categories