By wearing a mask of an animal the shaman becomes spiritually the animal whose masks he carries. In all traditional cultures by wearing a mask, in a festival or ceremonies you transform yourself, “Becoming Another”. This is the title of the exhibit at the Rubin, an exhibit of mask from various Himalayan traditions.
In Tibetan Buddhism Mahakala is a represented as a wrathful deity but it is considered to be the fierce emanation of Avalokiteshvara, the bodhisattva of compassion. But the wrathful manifestation comes from the desire to protect the Dharma from corruption and degeneration caused by impure thoughts and actions, Mahakala being one of the protectors or Dharmapalas in Vajrayana Buddhism.