Goddess Pratyangira is an Ugra Avatar or powerful incarnation of Mother Goddess Shakti. One school of thought is that Pratyangira Devi is an incarnation of Goddess Parvati. She appeared when Shiva took the Sharaba Avatar to control the Narasimha Avatar of Vishnu.
Goddess Pratyangira is a female form of Narasimha and the tradition has it that she appeared to control both the Narasimha and Sharaba Avatars.
Kali Sahasranama Stotra refers to Pratyangira Devi as Narasimhika. Some other texts associate her with Bhairava form of Shiva.
Pratyangira Devi has the face of a lion. She has four arms. In Tantric worship, she is black in color and sometimes depicted as nude.
This form of Mother Goddess is beyond imagination. She takes this angry form to keep Adharma under check. She appears to restore dharma.
She is propitiated for protection.
Goddess Pratyangira an attempt by human mind to give form to the formless Supreme Truth – here the dominating aspect is of fear.