Krishna Kali or Kali Krishna

The story of Goddess Mahakali taking birth as Krishna and Lord Shiva as Radha happened in a different Kalpa, manvantara, and yuga. 

Kali manifested as Krishna, Shiva as Radha

Whereas, Lord Vishnu's Krishna avatar and Adishakti as Radha appeared in the 28th Dvapara Yuga of the Vaivasvata Manvantara within the Shweta Varaha Kalpa.

 

Kali takes birth as Krishna, and Shiva as Radha

As stated in the Sri Devi Bhagavat Purana, once, Lord Shiva, along with Bhagwati Devi Parvati, was wandering in a temple situated at the pleasant peaks of Mount Kailasha. Seeing the most beautiful form of Parvati, Lord Shiva thought in his mind, “Female birth is fantasizing “. Then touching the lotus face of the Devi with his hands, who is beautiful in all Her limbs, spoke in His love-filled, sweet tone-

Lord Shiva said- “Oh, Durge, by your grace, all of my wishes are fulfilled; now there is nothing left to ask for. But oh, Sharvani, I have another wish. Oh, Shive, if you are gracious to me, please fulfil it as well.”

Devi Said, “Oh Shambhu, you are my beloved. What other desire you have, express it, I will fulfil as well.”

Lord Shiva said- “Oh Devi, if you are appeased with me, so, at my request, take birth anywhere on earth assuming a male form, and I will incarnate in the form of a female. Like this time, that I am your beloved husband, and you are my wife, who is dearer to me than my life, this domestic love will continue to prevail at that time as well. Oh, Devi, who is the fulfiller of the desires of Her devotees, please, fulfill my desire.”

Devi said, “Mahadeva, Lord, for your pleasure, I will take birth as Krishna in the house of Vasudeva. And oh, three-eyed one, for my delight, you take a feminine birth.”

Lord Shiva said- “Oh Jagadhatri Shive, for begetting you in male form, I will take the form of your beloved Radha, the daughter of Vrishbhanu, and roam with you. My eight other partial incarnations will be beautiful-eyed Rukmini, Satyabhama, and other astha-bharyas, who will incarnate on earth.”

Devi said, “When I incarnate as Krishna, my friends Jaya and Vijaya will also take male births as my friends Sridam and Vasudam. And Lord Vishnu will take birth as my elder brother, named Balram. He will be famous for his great strength, immense love, and devotion towards me.”

It is also mentioned in the Mahabhagavata Purana and the Linga Purana that Lord Shiva took the form of Radha in a past Kalpa and Goddess Parvati incarnated as Krishna. This divine play also involves a role reversal, where Shiva experiences love as a devotee (Radha) and Parvati embodies the divine lover (Krishna). 

Krishna Kali 

There are some Hindu scriptures, like Tantrarajatantra, which glorify Lalita. It is said that Lalita enchanted men, and to enchant women, Lalita took the form of Krishna. In the Lalita Sahasranama, Lalita is indeed described with names connecting her to Vishnu and Krishna, such as "Govinda-rupini" and "Vishnu sahodari". In the Todalatantra, Kali and Krishna are equated or seen as aspects of each other. There are Agam texts which equate 10 avatars of Vishnu as avatars of Dash Mahavidyas. In the Sri Kali Sahasranama Stotra, in Kali's 1008 names of Goddess Kali, the following names appear: Krishna, Krishnadeha, Krsna, Radha, and Devaki.

The idea that Krishna is Kali and Kali is Krishna appears in some Tantric and Shakta-Vaishnava syncretic traditions (primarily in the Tantric, Shakta, and Bengali Vaishnava-Shakta syncretic traditions), but it is not universally accepted among all schools of Hinduism.

There is an interesting story mentioned in many ancient Bengali literatures -  

In Vraja, every night, Krishna would play his flute in the forests, and Radharani would slip out of her house to meet Krishna. Radharani’s husband, Ayan, was unaware of this, so his sisters, Jatila and Kutila, informed him. This infuriated Ayan, and he went to catch Radha red-handed. Krishna, being aware of the future, asked Radharani to collect wildflowers and fruits and sit down as if she were worshiping. Radharani did what Krishna asked her to do. Krishna then took the form of Kali, the family goddess of Ayan. When Ayan came to the woods and saw Radha, he saw her worshiping Goddess Kaali and was very happy.

This story explains the divine connection between Goddess Kali and Lord Krishna, Kali being the maya (power) of Krishna. 

The Brhadyoni Tantra offers a striking story about Krishna’s connection to Kali. It describes how Kali descended to Earth and placed her yoni (a symbol of divine femininity) in the eye of a peacock’s tail feather before incarnating as Krishna in the womb of his earthly mother, Devaki. Later, during his divine play with Radha and the Gopis, Krishna noticed the yoni symbol in the peacock’s feathers. He plucked one feather and placed it on his head as a reminder of his connection to the divine feminine. This act symbolizes the union of feminine and masculine energies and the quest for inner balance.

Krishna Kali form of Krishna symbolizes a divine oneness of the Supreme Power. This unity blends the Vaishnavism and Shaktism, the incorporation of Kali into Vaishnava traditions and Krishna into Shakti worship. The concept of Krishna-Kali as one form beautifully reflects the harmony of divine energies and balances the masculine and feminine powers.