Do not think this mantra is only for external ghosts. The greatest demon is the ego. When you experience overwhelming anger, suicidal depression, addiction cravings, or irrational fear, sit on a cushion, take a fierce posture (straight spine, eyes slightly open and sharp), and chant the mantra loudly. The Phat is the liberating sword that cuts the root of self-grasping.
The universal sound, representing the beginning of the invocation. om vajrapani hayagriva garuda hum phat
A wrathful manifestation of Avalokiteshvara (the Buddha of Compassion), Hayagriva is identified by the small green horse heads emerging from his crown. His "wrathful compassion" is a fierce energy that destroys ego and attachments. Do not think this mantra is only for external ghosts