Navchandi Yagna is a Nav Durga Puja, a sacrificial rite which involves chanting of Saptashati Mantras to fulfill our desires and remove all sufferings. A person is blessed by all the supreme deities, including Lord Ganesha, Lord Shiva, Nav Grahas and Nav Durga, just by performing Navchandi Yagna Puja.
Even the ancient Upanishads find the mention of Navchandi Yagna Puja, wherein it states the elaborate rituals along with the benefits. These sanskrit texts document the procedures to be followed to invoke each of the nine energies of Maa Durga and how it can benefit us.
Performing a Navchandi Yagna Puja is said to bless the devotee with immense energy that helps ward off the negative energies and hardships in life. Navchandi havan involves chanting of Sapthasati Mantras which bears equivalent status as Ashwamedha in yagnas and Hari in Devas as mentioned to Damara Tantra. Bhuvaneshwari Samhita also describes Sapthasati Mantras as eternal like Vedas themselves.