Nice example of a worldspanning order and their role. Would have liked to know more about the structure of the organisation. Is there a central headquarter or is it more of a network of equal regional bases? How are decisions made? Is there a grand master or a council?
A few details on things like the binding vows (which suggests they have a restraining role on wizardry) and perhaps also different factions with the guild would be nice extra touches. Go to Comment
A golden skull contains the spirit of a person who has been magically entrapped in an ethereal undead status by an ancient ritual. The person was boiled alive in a golden mixture until nothing remained of him except the bones, now covered by a golden layer. Whoever has these golden bones, controls the spirit and can command it. It can assault the living with wind and storm. Manipulate objects and communicate with the living. (Inspired by Anne Rice, Servant of the Bones)