Sri Swami Vishwananda talks about the seventh form of the Divine Mother called Kalaratri Devi.....

 Maa´s seventh form is Kalaratri. Her complexion is as dark as the night, symbolizing infinity. Her cascading hair is let loose and she is seen wearing a garland that radiates light as bright as lightning. She is mounted on an ass. She has four arms. Although she has a menacing appearance, her devotees need not fear her. In this form Devi is always ready to give anything you ask. She accepts everything from the devotee, not only the good, but all the bad, negative qualities. She just absorbs them, so that we can be free, free from the little demons that we create in our mind and who are all jumping left and right.