ORACLES ARE VERY IMPORTANT. They are the backbone of practically all magic in some way or another. They're also pretty rare to come by. Oracles work by contacting the Patrons (essentially Gods) of different things, depending on the situation. For example, to resurrect somebody they would have to hit up the Patron of the person's race, the Patron of their class, the Patron of Death, Patron of Time, Patron of Spirits, Patron of Oracles and sometimes others in order to get permission for the resurrection to take place. It's a very tiring job.
Oracles are a completely defensive class. They have no offensive abilities because the Patrons refuse to fight on their behalf. To put an Oracle on a battlefield is paramount to treason as they are highly revered in society. It's also plain dumb, as they're sitting ducks.
Oracles are much rarer than other classes. They have a low birthrate to begin with but their numbers also suffer as the process to become one is long and arduous - often taking a person's entire lifetime. They are sought after as fortune tellers or prophets, although it is known that they aren't. The Patrons don't give them the secrets to the future (or any other information that would disrupt their power over their creations). Many become rich as royal advisers or as members of resurrection shops.