Warlock is a catch-all term for unsanctioned spellcasters who practice pact magic. By forming some sort of a bond between themselves and an extraplanar entity, they are able to tap into great reserves of power.
Pact Magic came into prominence in the old empire more than five hundred years ago. Within a century, it is said that devils walked the streets openly and mortals were snared in a web from which they very nearly did not escape. Fortunately, the decadent lifestyle of the ruling class led them to ignore the seeds of collapse within their infrastructure. Infernal creatures of hideous depravity cackled as the mortal illusion of control was stripped away, and these cruel creatures began a reign on earth that would serve as a brief, brutal preview to the eternity being dragged through the nine hells that awaited most of the imperial citizens.
But it could not last. The pressure of living in such harsh times gave rise to heroes who were not afraid to stand up to the Devils. The last vestiges of Infernal control in the realm of mortals were cast off four hundred years ago, and now, little remains but ruins.
However, not all of the ancient ways were stamped out. Here and there, books from the imperial era surface, or a whisper in the night leads some new soul down a potentially damning path. Worse still, some warlocks are born with their power, not knowing the circumstances of the pact that has bound them to it. What terrible price will they pay for power?
The International Guild of Magic has declared pact magic to be harmful beyond all measure, and goes to great lengths to root out and destroy cults and cabals as they arise. No distinction is made between Fey, Star, and Infernal pacts as it is generally believed (and often true) that pacts made with capricious fey or unknowable entities from beyond are just as harmful as those made with the hordes of Hell.
Warlocks in Shade