Dakini-Varnini is a kind of spirit, many consider them to be evil spirit, haunting forests, dirty and unkept places. They are believed to thrive on flesh of animals and humans. The birth of Dakini is associated with Goddess Parvati.
Goddess Parvati descended to bathe in the Mandakini Lake.
She lost track of time while playing in the water with her female companions (sakhis).
After some time, her companions became exhausted and distressed from hunger and
thirst due to their water-play.
They repeatedly pleaded with the Goddess for food. Parvati herself had turned from fair-complexioned (Gauri) to dark-complexioned (Krishnangi) out of hunger. But it was extremely difficult to find food in the forest before reaching Kailash. Yet, these companions were like her own children. How could she keep them hungry?
And who doesn't know that hunger is as terrible as fire? It
burns fiercely, consuming everything from the stomach to the brain. Thus,
severely distressed by hunger, even beautiful companions adopted the monstrous
forms of 'Dakini-Varnini'.
Therefore, Parvati severed her own head with her
fingernails. She quenched the thirst of her two companions with her own blood.
At the same time, a stream of the blood also satisfied the thirst of her own
severed head.
During Shyama Puja (Kali Puja) in Bengal, the companions or attending
deities (avarana) of the Goddess, Dakini and Yogini, are often seen flanking
her, where they appear in terrifying forms. However, in the mother-form (Matri-kalpa)
of Dakshina Kalika, they are not present. Their foundation is entirely esoteric
and philosophical. They are only mentioned in certain specialized meditations (dhyanas).