According to my experiences, a Yakshini is not any kind of external spirit, ghost, or fairy; but she is a manifestation of nature's invisible mystical Tantric energy. When the seeker's mind and the vibrations generated by the Yakshini invoking mantra align at a specific frequency, that energy takes form. The seeker experiences this form through his own subconscious mind.
Prophet666
Hindu Mantras, Tantric Rituals & Occult Secrets