The practice of "A Rosary for the Souls of Priests suffering in Purgatory" obtains singular graces for those who pray it sincerely. It brings about conversion among sinners, reawakens the fervour in lukewarm Christians, turns priests into zealous apostles, alleviates suffering with a joyful resignation to divine will, and makes the soul desire perfection.
In order to pray this devotion, there is a special rosary you can find here: Corona Anime dei sacerdoti defunti.