This mantra to Chinnamasta is not for the faint hearted! She is a challenging goddess to work with, and will call you out on your bullsh!t, and not let you hide behind your story.
She's also not one of the glamourous, easy to look at goddesses - naked, with a necklace of skulls; dancing on the coupling forms of the god of desire and his consort; holding a bloody cleaver in one hand and her own severed head in the other whilst she and her two attendants drink the blood that is spouting from her severed neck!
If you can find the courage to work with her, she will reward you for it, though.
Here's the mantra:
Om aim hrim klim Vajra-Vairochanyei hum hum phat swaha
ohm eem h-reem kleem varj-rah vie-ro-chan-yay hoom hoom fut sva-ha
There's no direct translation; Vajra-Vairochani is one name for Chinnamasta and it means "thunderbolt lightning of spiritual awakening". The other words are mostly seed sounds meaning beauty, fire, light, spiritual self-realisation and destruction of illusion.