Aggamon was the ruler of the Purple Dimension. Dr. Strange encountered him after two burglars who had broken into his Sanctorum were transported to the Purple Dimension. To free them, he offered himself as a prisoner to Aggamon, but when the burglars had been released, Strange challenged Aggamon to a mystical duel. In the ensuing contest, neither could gain an upper hand, but both of them grew constantly weaker. Fearing that Strange would rather die than surrender, Aggamon gave up and let Strange return to Earth.