The Energy Synthecon was created by Chleee, a member of the alien race the Glx, from a prison shackle attached to the wrists of Leroy Jackson and Johnny Anvil. The Synthecon was given to the escaped convicts as a reward for saving the alien's life and because of it, the two men were granted tremendous powers which they used to battle the Hulk, resulting in the Energy Synthecon's destruction.
A company called the Deterrence Research Corporation (DRC) repaired the golden manacle and returned it to Hammer and Anvil. The duo fought other heroes while in the DRC's employ, and the Synthecon was again destroyed by Spider-Man and members of the Guardians of the Galaxy. The DRC rebuilt it, but a powerful venom blast by Spider-Woman left it inert.
It is unrevealed if DRC repaired the Energy Synthecon again, but Hammer and Anvil wore it one last time in a bout with the Hulk before the Scourge of the Underworld shot and killed Hammer. The symbiotic bond the Synthecon created between the wearers took Anvil's life seconds after his partner died.