In traditional Hindu Mythology and folklore there is no fixed definition for a mystic being known as the Pishacha. The Pishacha is commonly referred to as a malefic Demon who is said to feed on the flesh of living and dead beings, including humans and corpses of dead humans. The Pishacha, who is classified as a Demon should not be confused with Bhoot-Pret, who are classified as spirits or souls of dead people who have not attained Moksha[Liberation] and are not always harmful or malefic.
Many regular readers of this site would have no doubt noticed several references to the Pishacha in many earlier posts published on this site especially those pertaining to exorcism rituals, spells and charms. This site gets all kinds of visitors looking for Voodoo Spells of all kinds and the Demon Summoning Mantra given below is for the people who are looking for this specific spell.
The Mantra given below is the Pishacha calling Mantra and should be chanted continuously in order to generate the necessary vibratory energies and frequencies, which are needed to make a Pishacha manifest before the chanter of the Mantra.
ॐ ह्रौं ह्रौं पिशाचस्याय स्वाहा ||
Om Hroum Hroum Pishaachasyaaya Swaha ||
The Tantra does not mention any fixed number of Mantra Chants nor any kind of specific Tantric procedures or rituals in order to perform this Mantra Experiment to make the Demon manifest. It is also unclear as to what will happen after the Demon has appeared before the practitioner.
There are many tales about the Pishacha being put under a Vashikaran Spell of attraction by certain powerful Tantriks, Witchcraft practitioners and Occult Spell Casters. However, I have not witnessed the supernatural occurrence of the Pishacha being controlled by any person.
Hence, I consider the summoning of a Demon to be a most dangerous and life threatening Mantra Experiment. The Pishacha can also be classified as a Vampire because some people see a similarity between the Pishacha and the Vampire and believe that it is one and the same paranormal mystic entity.