In 1873, after interrogating bandit leader Ace, Hawkeye, Thor, Moondragon and Two-Gun Kid enter Kang’s citadel disguised as Ace’s gang, but Kang easily sees through their deception and stuns them with his security devices. In the modern day the Avengers escape Dr. Spectrum’s energy cage by combining Vision’s phasing ability with Captain America’s shield. Back in the past Kang toys with his captives, unleashing a giant monster on them, but underestimates Thor, who escapes and confronts him. While Kang and Thor’s battle moves outside the citadel, Two-Gun Kid panics as he faces a creature beyond his ken, until Moondragon takes down the monster with a mental bolt. Outside Thor shrugs off Kang’s strongest attacks, until Kang overloads his armor, killing him by scattering his atoms across time, causing his citadel to vanish too. Immortus briefly appears to tell the Avengers that with Kang gone, the conqueror will never become Rama-Tut again, nor will Rama-Tut become Immortus. And with that, Immortus fades out of existence.
Rama-Tut ponders his failure to stop Kang, and resolves to become a true master of time, leading to his becoming Immortus.
Immortus lies about being wiped from existence here, as revealed in Thor #282, ’79.