Mahavidhya Sadhana can be one of the most intense Sadhana in spirituality. There are 10 goddess in mahavidya Sadhana and all are originated from the concept of Shakti. Shakti and Shiva plays an important role in creation and destruction of the universe. While Shakti is the dynamic form of energy, Shiva is the masculine force. Mahavidya Sadhana is generally accompanied by tantric practices. The wrong concept about tantra is it involves spooky activities and sex. The notion about tantra is incorrect though it may involve sex, alcohol and even blood in rituals. While sex, alcohol, blood can be categorized as negative in spirituality, all are offered in tantric practice after removing the negativity.
Tantra practice involves working with both body and mind. So it involves both the physical and cosmic body. It is an intense process and helps in faster spiritual progress. However, there is no guarantee that one can attain spiritual progress in higher level while doing the practice. One needs to surrender to the Supreme while doing the practice. It is finally the Supreme who decides the spiritual progress of a person. Among the ten mahavidyas, each mahavidyas gives a different path to accomplish. While few mahavidyas can bestow one with prosperity, few can take one to the highest level of awareness and liberation . Few can even bestow you with vaksiddhi ( whatever you say will come true) and siddhi. Though the conclusion for practicing mahavidya can remain same- salvation and freedom.
Iconography in mahavidya
The Iconography of each goddess in mahavidya can be fierce and intense. The fangs, voluptuous breast, skulls shown in the icons are questionable to many. I have already written an article on significance of erotic temple. We can relate few to the erotic part of energy and the underlying fact of these iconographies can be rising up from duality.
Good and evil are duality of nature but beyond that there is a world of consciousness and awareness. When we rise above duality, we find the inner self, the inner happiness. We can conclude that the main concept of Tantra can also be rising above duality, rising above good and evil, rising beyond mind and self.