The Defenders, Vol. 1 #77A (1979)

Waiting for the End of the World!
Tracking James-Michael Starling to Las Vegas, they find him just as he escaped the clutches of Ruby Thursday and his growing power level causes him to lash out on the world. While elsewhere the Hulk has the name of the Unnamable implanted into his head by the creature he is fighting. It leaves soon afterwords. Fighting off both Thursday and the aliens come to destroy Starling (who are being decimated by said individual) Moondragon learns that the aliens created both Omega and James-Michael as a part of an experiment to advance their races evolution so that they may continue. Each creation was disguised as a native of the dominant race of the planet they were left on. The creation that would become known as Omega was given the power of the entire planet he lived on and in his passing he passed along that power to James-Michael. The Defenders defeat Ruby Thursday, seemingly killing her when they smash her head open, and Moondragon reveals James-Michael's origins and that the power he holds is too much. Not wishing to harm his friends, James-Michael then turns his powers inwards and kills himself. After the battle, Moondragon chastises the Defenders for their rash action as it led to the extinction of an entire alien race, and after she gives James-Michael and Omega a proper burial, she does not want them to contact her for help again.
Release Date: 1979