Origin

Hammer Jackson and Johnny Anvil are two prisoners on the chain gang that are linked together at the wrists. They manage to escape prison and run into an alien that is suffering from some injuries. Hammer shoots the alien with a .38 caliber pistol he took from a guard. The alien does not die but actually recovers because it absorbs the metal and sustains the alien's internal existence support systems. The alien repays the two convicts by transforming their chain into an energy synthecon and grants them superhuman strength.  Hammer and Anvil return to the prison to exact vengeance but run into the Hulk. During the fight, the Hulk manages to break the energy synthecon and the two men went insane since they were both physically and psychically linked. The two convicts are apprehended and sent back to prison.   

Creation

Hammer and Anvil was created by Len Wein and Herb Trimpe in 1974 and first appeared in The Incredible Hulk # 182.

Story Arcs

Months later, Hammer and Anvil regain their sanity and are released from prison by Ivor Carlson who was the head of the Deterrence Research Corporation and hire them as corporation employees. Carlson had his scientist repair the energy sythnecon and altered it so Hammer and Anvil are no longer mentally linked to the band. The two men were hired to eliminate Spider Man for causing so many problems for the DRC. Spider Man is captured and held captive but is assisted by members of the Guardians of the Galaxy. The synthecon is destroyed when Martinex freezes the band, rendering it brittle and then it is shattered by Spider Man. Hammer and Anvil are defeated once more. The DRC would repair the synthecon once more and the two convicts would clash with Spider Woman on numerous occassions. Spider Woman defeats both men when she shoots bioelectrical energy into the synthecon and it became inoperative. Sometime later both men regain the synthecon again and encounter the Hulk in a Nevada desert. Hammer is shot in the face with an explosive bullet by Scourge of the Underworld who was disguised as a Native American Shaman. Having been linked by the synthecon to his dead partner, Anvil died soon afterward.

Two (different?) men have taken up the identity of Hammer and Anvil but their true identities are unknown. They would run into Colleen Wing and Misty Knight when the two ladies shakedown the Rascal Tavern where numerous costume criminals hang out. The two ladies beat down on some bad guys when they try to get answers on  8-Ball and Freezer Burn after they were killed for stealing a microchip from Ricadonna.   

Powers & Abilities

The energy synthecon granted Hammer and Anvil superhuman strength and durability. The synthecon radiated with energy that would shock or burn anyone that touched it.