Various Tantrik texts like Mundamala Tantra and Todal Tantra mention the Dash Mahavidyas in respect to the Dashavatar. For example in Todal Tantra CHapter 10 we find the following declaration:
"Shri Shiva said: Tara Devi is the blue (fish) form, Bagala is the tortoise incarnation, Dhumavati is the boar, Chinnamasta is Narisimha, Bhuvaneshvari is Vamana, Matangi is the Rama form, Tripura is Jamadagni, Bhairavi is Balabhadra, Mahalakshmi is Buddha, and Durga is the Kalki form. BhagavatÌ Kali is the Krishna murti."
Is there any logic to these comparisons? Also, if Kali is equivalent to Krishna where does Shiva come into the picture?