Kali - Mahavidya

Kali stands on Shiva

Kali is one of the Mahavidyas. Krishna avatar of Vishnu is portrayed at the bottom.

Image of Satguru Sivaya Subramuniyaswami
Yes, willpower is the key, the must, the most needed faculty for spiritual unfoldment on this path. Work hard, strive to accomplish, strengthen the will by using the will.
—Gurudeva