Chhinnamasta Yantra along with its Mool Mantra is considered very effective medium to fulfil Chhinnamasta Sadhana.
श्रीं ह्रीं क्लीं ऐं वज्र वैरोचनीयै हूं हूं फट् स्वाहा॥
Shreem Hreem Kleem Aim Vajra Vairochaniyai Hum Hum Phat Svaha॥
Ashtottara Shatanamavali of Chhinnamasta
information on Goddess Chhinnamasta
list of Chhinnamasta Mantras
10 forms of Shakti