A purba is a dagger-like stake with three blades that helps tantric practitioners overcome their aversions to substances that are typically considered abhorrent, like pus and blood. Pierced with the purba, the unsavory substances are ritually transformed into wondrous substances, such as nectar.

Crowning this purba are a half-vajra and three heads of the tantric enlightened being named Vajrakila, who presides over powers of transformation from wickedness to compassion. Each of his faces has been wrought of a different metal alloy in the imperial workshop of the Chinese emperor of the Ming dynasty. The luxurious quality of the endless knot motifs, the crocodile heads, and the snakes twisting down the center of each blade indicate Chinese imperial workmanship.