The archmage and heirophant are both specialists of their respective Source. Each focused on ever honing their singular skills. The overmage instead focuses on blurring the lines of power and removing any distinction between sources at all. Shadow touches arcane, divine threads temporal, and the Overmage stands at the center of it all.
Role: As a specialist in versatility the Overmage tends to be more fluid than his spellcasting brethren, utilizing any power crossed and empowered with the resources of all his others he rarely runs out a magic that is useful before he decides it is time to do so.