Psyche - P

Petitioner = Petitioners are a special class of Adepts who may or may not develop supernatural traits from Degree progression, but instead from the interaction with a specific type of Supernatural. Priests develope supernatural abilities from the Saints they venerate, Archangels receive them as gifts from Celestial Patrons, etc. 
Phantasmagoria = When the material world is 'invaded' by the forces of the Realm of the Psyche. See Phantasmagoria for more info.  
Primordials = There seems to be a connection or overlap between some of the beings found in the Realm of the Psyche and the Primordials. The Primordials are ancient beings who predate the universe or most universes. They are also immensely psychic (the greater among them are, anyway). Shades are horrified of Primordials because they are gigantic and nearly unstoppable. The entire Order has a policy of seizing any opportunity to scuttle their plans or strike out against them.
Psychics = Psychics are the natural recruits and results of the Order of Mithras. The entire Order exists as 'ultra-Psychics' whose connection to the World of the Psyche eventually becomes so powerful that they are subsumed by it and now exist totally as pure consciousness.