When fed by a hose into the back of his head, Venom causes a huge and immediate increase in muscle mass, although the change is temporary. Venom is both highly dangerous and illegal.
Bane originally sold Venom to a number of regular buyers, but these sales dried up when the Cult of the Kobra took over the Venom factory on Santa Prisca. Kobra combined Venom with Project Blockbuster to produce an even more powerful and permanent drug, Kobra-Venom, which they then intended to sell to the Light's associate, Sportsmaster. This deal was interrupted and the Venom factory destroyed by the Team.
Background in other media
Venom is a chemical created by Bane that enhanced his muscles, granting him superhuman strength and durability. Later, in the pages of JSA Classified, it was revealed it was largely based on Hourman's Miraclo formula.