Ma Katyayani is the sixth form of the Goddess Durga.  There are several stories about Ma Katyayani.  One of them is from the Karveer Mahatmya ( a collection of legends about  Karvir,  now known as Kolhapur in the state of Maharashtra in India.  According to the Mahatmya, Goddess Mahalaxmi went with her army to Karvir to fight against the demon Kolhasur.  Raktabeej, an ally of Kolhasur, had a boon that whenever a drop of his blood fell on the ground, another  Raktabeej would be born at that spot (rakta means blood while beej means seed). In the battle that ensued between the goddesses and demons, Goddess Katyayani swallowed all of Raktabeej’s blood to prevent it from falling on earth.
There is a temple Kolhapur which celebrates the victory of Goddess Katyayani, along with Bhairav, over Kolhasur.