Bhairava Mudra invokes Lord Shiva
A mudra (i/muˈdrɑː/; Sanskrit mudrā, "seal", "mark", or "gesture"; Tibetan: ཕྱག་རྒྱ་ THL chakgya) is a symbolic or ritual gesture in Hinduism and Buddhism. While some mudras involve the entire body, most are performed with the hands and fingers. A mudrā is a spiritual gesture and an energetic seal of authenticity employed in the iconography and spiritual practice of Indian religions.
One hundred and eight mudras are used in regular Tantric rituals.
In yoga, mudras are used in conjunction with pranayama (yogic breathing exercises), generally while seated in Padmasana, Sukhasana or Vajrasana pose, to stimulate different parts of the body involved with breathing and to affect the flow of prana in the body.