According to legend, on this day, Goddess Durga begins her journey towards Earth. Scriptural recitations and prayers are sung to summon the Goddess so she may efface all evil. In destroying evil, Durga transforms into Goddess Kali, who is regarded as her most ferocious avatar.

Is Durga Kali Parvati same?

Ambika, Durga Parvati and Kaali are the same because they all are Adishakti Avatar. Adishakti is a Goddess and wife of Lord Shiva, She was first called Sati but she died so then she took rebirth as Parvati, daughter of King Hemavan.

Why Durga is called Kali?

Kinsley writes that Kali represents "Durga's personified wrath, her embodied fury". Other origin stories involve Parvati and Shiva.