Goddess Prachanda Chandi, also known as Prachanda Chandika, is believed to be the sixth of the Mahavidyas. She rules over the firmament - the apparent surface of the imaginary sphere on which celestial bodies appear to be projected. In the cosmos, the pathway of the Devas is Prachanda Chandi. She is today popularly known as Chinnamastika.
She is the deity known in the Vedas as Indrani. Another particularity here is that the manifest and unmanifest effulgence of the firmament is Prachanda Chandi. She is that the transforming which serves as the weapon of the Supreme.
She is known as Vajravairochaniya. Vajra is the weapon of the Supreme. On account of her brilliance she is known as Vairochaniya.
In the individual she is Kundalini Shakti. Prachanda Chandi springs forth from the same source, muladhara, in the individual. She goes straight to Sahasrara and generates the flow of Amrita from there, causing profound ecstasy. It is by her valour that a subtle passage is opened in the crown of the head of an earnest updsaka or yogi. This is the experience referred to by the text of the Taittiriya Upanishad, 'vyapohya sirshakapale' (parting the front and back of the skull).
As the conveyor of the force of Prachanda Chandi, sushumna is associated with her. When a siddha (spiritual adept) is urged to go to higher spiritual regions, then also, this opening of the skull takes place. The two associates of Prachanda Chandi, Dakini and Varnini, are the ida and pingala naddis respectively.
One who aspires to get in tune with cosmic Divine Power should adore Prachanda Chandi.
She is described as holding in her two hands her own severed head and a sword. Her maids Dakini and Varnini are standing on either side of her. Three jets of blood spurt forth from the neck of her headless trunk and fall into the open mouths of the two maids and her own mouth in the severed head held in one of her hands. She is standing on the bodies of Kama, the god of love, and Rati, his consort.
This picture is highly symbolic. The severed head signifies the severance of the base ego. Of the three jets of blood, the central one denotes the irrepressible flow of power through the central nddi, sushumna, and its assimilation; the other two jets denote the flow and assimilation of power through the Ida and pingala naddis. Her standing victoriously over the united bodies of Kama and Rati represents the conquest of the sex-urge which is the very basis of spiritual perfection.
Source – notes taken from The Ten Mahavidyas of the Mother By Viswanatha Swamy published in The Mountain View Magazine 1976 January issue page 22 - 23