This mantra combines three powerful deities from Tibetan Buddhism: (power/wrathful energy), Hayagriva (fierce compassion / horse-headed), and Garuda (wisdom overcoming serpents/obstacles). The seed syllables hum (stabilization) and phat (cutting through ignorance) amplify its force.
By invoking the "destructive aspect" of the Vajra, the mantra aims to destroy all obscurations to the Dharma (the path of truth). om vajrapani hayagriva garuda hum phat