Aggamon

For at least a millennium Aggamon had ruled the Purple Dimension, from which he tricked natives of other dimensions into entering his realm and he forced them into slavery in his mystic gem mines. In recent years, two thieves stole Doctor Strange's Purple Gem, which transported them to Aggamon's dimension. Strange, sworn to protect all humankind, confronted Aggamon, who offered to return the men in exchange for Strange's servitude. Strange agreed, but once the thieves were freed, he declared he would leave servitude and challenged his opponents to a mystic duel. The two sorcerers were stalemated for hours, eventually weakening their life forces until Aggamon, unwilling to risk his life, surrendered. Revealing he had cast a spell preventing Aggamon's full recovery unless he freed his remaining slaves, Strange then returned to Earth with the two thieves. The two thieves moved by the experience, turned themselves over to police custody. Later, while Doctor Strange was fighting his second battle against Dormammu, Aggamon was one of several rulers of extra-dimensional realms who witnessed the event. He also sold his gems to sorcerers throughout the multiverse which were used to focus, store, and/or amplify mystic energy. Clea also extorted Aggamon into helping her reclaim he role as ruler of the Dark Dimension.