Metamorpho is back with Superman and Batman in World’s Finest 226 (Nov/Dec 74), but not in the adversarial fashion implied by the cover.
Instead, Haney, Dillin and Blaidsel have Rex Mason get sent off by Simon Stagg on a mission that puts him into contact with a foreign dictator. Superman and Batman are on a mission to the same fictional country to retrieve a defecting scientist, Vronsky.
When he meets the heroes, Metamorpho happily turns against his host, and finds the one they are looking for.
But a more devious plot is underway. The scientist is really a double, infected with a highly contagious disease with which the dictator hopes to wipe out the US. But the heroes figure out the plan, and switch the orders so the phony Vronsky only manages to infect the dictator before dying.
Not a bad story, and one good page of Metamorpho using his powers, but otherwise not a very Metamorpho story.