Bhadrakali
Bhadrakali is the terrific form of Sati who emerged from her wrath.In Sri Durgashtottarnamastrotam, Bhadrakali is 98th name of Durga, the first being Sati.
In Argalastrotam, Bhadrakali is the 4th name of the Goddess Chandika or Durga. This form is said to be a form that gives all the auspicious things to her worshipers, that is why she is called Bhadra.
In one of her incarnation the Goddess Durga was Sati, the daughter of Daksha Prajapati and was married to Lord Shiv.
One of the story from Indian mythology tells us about a sacrificial ceremony organized by Daksha in which he intentionally not invited Lord Shiv to participate. Sati asked him to go to her father's ceremony but Shiv refused to go on the ground that he was not invited. He also advised her not to go there uninvited. She insisted to go there on the ground that she should go to her father's house even if she is not invited. At last, she went alone and found that there was no place for her husband. She was then infuriated and in her wrath Bhadrakali emerged to disrupt the ceremony. This form of Sati is called Bhadrakali.
This terrific form is also referred in many Hindu sacred texts, many of them are mythology and many are tantrashashtra.
In Durga Saptashati of Markandeya Puran this form is also referred as Goddess Durga.
It may be mentioned here that in the sacred texts in Durga Saptashati and its related texts included while it is recited tells us that the Goddess Durga or Shakti manifested herself in three forms and became consorts of Lord Brahma, Lord Vishnu and Lord Shiv.
In the same Durga Saptashati, we come to know that Mahakali, Mahalaxmi, Mahasaraswati etc were the various form of the Shakti, the Goddess Durga.
Bhadrakali had twelve arms with weapons. In some of the sacred texts we find her with eighteen arms and in some ten arms.
In the fourth chapter of Durgasaptashati, gods pray her after the Goddess Durga killed Mahishasur with all his leftinants and demons. They called this incarnation Bhadrakali, because she had manifested in this form for the welfare of the world.