Nila Devi, also known as Neela Devi, is the ferocious form of Durga. She is also called Tara, one of the ten manifestations of the Feminine Energy (Devi) Ref; Dasha Mahavidya, Reference of Neela Devi as the third consort of Maha Vishnu, as I understand is not referred in any Puranas, but Neela Devi, Tara, has reference in TANTRA SHASTRAS