Within a decade, he became the world's greatest living authority on alchemy, having discovered or concocted countless potions with bizarre properties. Haughty and cunning, Diablo began to put his alchemical knowledge to use for personal gain. Journeying to Transylvania to investigate its legendary secrets, Diablo settled there and established permanent laboratory facilities. Under suspicious circumstances, he acquired a spacious castle and began work. Although most of his potions' effects proved transitory, Diablo discovered an elixir that could retard aging. Drinking it, he embarked on a reign of terror over the surrounding Transylvanians, until a mob of villagers caught him unaware and imprisoned him in a massive crypt. Diablo was trapped there until the 20th century, when he mesmerized the Thing of the Fantastic Four to free him. Not having aged appreciably during his century of confinement, Diablo began to plot his alchemical conquests anew. He has plagued humanity on numerous occasions, most frequently opposed by the Fantastic Four.