Exorcism
In Catholic practice the person performing the exorcism, known as an exorcist, is an ordained priest. The exorcist recites prayers according to the rubrics of the rite, and may make use of religious materials such as icons and sacramentals. The exorcist invokes God—specifically the Name of Jesus—as well as members of the Church Triumphant and the Archangel Michael to intervene with the exorcism. According to Catholic understanding, several weekly exorcisms over many years are sometimes required to expel a deeply entrenched demon.
Gabriele Amorth
Edward Peters, a professor of canon law, finds Amorth's claim to have personally performed 30000 exorcisms over 90 years "astounding". Even accepting Amorth's claim that only 94 of his 30000 exorcisms represented full-blown possession, that would have required roughly one case a month to be thoroughly examined and processed over nine years with hardly a break. Amorth believes that a person may be possessed by more than one demon at once, sometimes numbering in the thousands, which is what accounts for the high number of reputed demons exorcised.