Maha-Mudra is the most important of all Mudras. The practice of this mudra cures consumption, haemorrhoids or piles, enlargement of spleen, indigestion, Gulma (chronic gastritis), leprosy, constipation, fever and all other diseases. Life is increased. It confers great Siddhis on the practitioners.
The process by which the sun is brought upward and the moon is carried downward is called Viparitakarani Mudra. The positions of the sun and the moon are reversed. It is believed that the Yogin who practises this for three hours daily conquers death.
'Kha' means Akasa and 'Chari' means to move. The Yogi moves in the Akasa. The tongue and the mind remain in the Akasa. Hence the name, Khechari Mudra. By the practice of this Mudra the Yogi is free from fainting, hunger, thirst and laziness. He is free from diseases, decay, old age and death. This Mudra gives Siddhis to Yogins. Khechari is the best of all Mudras.
Shakti Chalana Mudra is a Tadana Kriya. Through the practice of this Mudra one can become a Siddha.
Vajroli Mudra also is called Yoni Mudra. This is not quite easy for all like other Mudras. You have to exert much in getting success in this. You must be perfectly established in Brahmacharya if you want sure success.