Pact Mage

A mage who casts magic via a spirit patron who also acts as a proxy to cast spells, including those that many other mages cannot. Pact mages do not learn magic the way that most other mages do, instead of learning spell formulas they learn how to invoke spells from their patrons. When a pact mage invokes a spell they create a signal to their patron, who manifests the spell and transfers it to the pact mage to hold and release (see Magic for information on the stages of spell casting). The invocation of a spell varies greatly based on the patron and their relationship with the pact mage, for example some demonic patrons require sacrifices in order to invoke a spell, while some fey patrons require the pact mage to never harm a wild animal. This means that a pact mage's patron dictates the spells a pact mage has access to, and the strength of those spells.
The pact that a pact mage forms with their patron is a powerful binding force that stretches through the Astral Plane to connect the two beings. Upon creation the patron gives the pact mage a special Spell Focus that is unique to the patron, it can be a piece of them as a lock of an oni's hair or something they made such as a wand made from a branch collected in a Nymph's forest. This Spell Focus is capable of transferring a spell manifested by the patron through the Astral Plane and to the pact mage to hold and release.
Because of the invocation, a pact mage is limited in the Arcane Discipline they can utilize, as they do not manifest the spell themselves. However if the patron and pact mage have access to the same Arcane Discipline then they can utilize its effects.
There is no limit on who or what can be a patron so long as the patron has the ability to cast spells. This means that although generally it is spirits that enter these pacts, it is possible for mortal or even divine beings to enter them as well. Notably beings such as the Ard-Ur enter into lucrative pacts with mortals in exchange for knowledge. Most gods however reject mortals trying to form a pact, often punishing those audacious enough to try.