It is widely believed that worshipping Goddess Bhadrakali on Amavasya or no moon day is highly meritorious. Symbolically, Amavasya represent spiritual darkness and Goddess Bhadrakali arrives as light and annihilates the darkness and ushers in the light of knowledge that all that is here is nothing but the Supreme Truth. Goddess Bhadrakali forcefully removes the darkness created by ego.
It is believed that Goddess Bhadrakali appeared from the matted locks of Shiva when he untied them and hit them on the ground on hearing the death of Goddess Sati. Another belief is that Goddess Bhadrakali appeared from the third eye of Shiva to kill Daksha Prajapati.
Bhadra means auspiciousness and Goddess Kali is one who provides us with auspiciousness. She removes all kinds of dirt covering the Supreme Truth like lust, anger, ego, hatred, ignorance and the though I am the body.
Kali Kali Mahakali Bhadrakali Namostute
Kulam Cha Kula Dharmam Cha Mam Cha Palaya Palaya