Since I just wrote a really long exegesis on the Mangog saga in THOR #154-157, I'm not going to spend a helluva lot of time on this null-myth selection, one of the many craptacular pseudo-epics that appeared in the pages of THOR after both Jack Kirby and Stan Lee departed the feature.
In keeping with my criteria for null-myths, though, my only reason for pointing to the mostly forgotten "Ego Prime saga" is to show how a good idea can go wrong in terms of its symbolic content.
The tale of Ego-Prime technically begins before #201, for it's a "B-story" that starts in issue #198 as a counterpoint to the main tale--one of many unimaginative takes on Ragnarok that followed the first, and arguably best, version by Lee and Kirby. In the B-story, Odin sends two Asgardian goddesses-- Hildegarde and Thor's gal-pal Sif-- to a planet called Blackworld. He doesn't exactly tell them what they're supposed to be looking for there, but eventually Sif and Hildegarde find out that the whole world is going through a rapid course of evolution from one phase of Earth-history to another. That is to say, one minute the goddesses are seeing a culture of knights in armor, and in the next, it becomes the culture of America in the 1920s. Though writer Gerry Conway had published some prose SF and supposedly knew the genre well, this is the sort of "magical SF" that makes juvenile Superman-stories of the Golden Age seem like Isaac Asimov by comparison.
Eventually the goddesses find out that the person responsible for the weird accelerated progress is an old friend: Tana Nile, one of the aliens called "Colonizers" who had appeared during the Lee-Kirby tenure. Tana Nile, under orders to find more habitable planets for her people, got the idea to travel to the surface of another Lee-Kirby creation, "Ego the Living Planet." Sans any scientific data or investigation, Tana slices off a chunk of Ego's "skin," takes it to Blackworld, and implants it in the planet's soil. Though the word "terraforming" is never used, apparently this was Tana Nile's intention. Because Conway didn't care to make her actions internally consistent, the alien does absolutely nothing to curb the effects of the planetary chunk, which takes on its own intelligence and a gigantic form that she dubs "Ego-Prime."
Then, just as Thor has returned to Earth, the creature for some reason teleports itself, the goddesses and their allies to the real Earth, since Ego-Prime plans to create a sentient "bioverse" and for some reason can't do it from Blackworld. There follows a lot of standard Marvel fight-scenes while Ego-Prime unleashes various menaces (mutated humans, giant ants) on the Asgardians.
So far, all of this is merely routine bad comics, taking innovative concepts introduced by better creators and dumbing them down. But while all the chaos is going on, the new A-story now gets a B-story, as Odin sends other agents to Earth to seek out mortals who share some mysterious common factor that Conway never bothers to expain. Then, just as Ego-Prime is about to destroy the world, Odin reaches down from Asgard and somehow transforms the giant into energy that he infuses into the three humans-- who then become three young gods. Odin sends the young gods off into some remote heaven to serve some obscure purpose that does not come to fruition for many years, when Roy Thomas enlisted Conway's "God Squad" (as some clever fan dubbed them) to play a role in his multi-issue "Eternals" plotline.
Lee and Kirby's "Mangog saga" is rife with dozens of inconsistencies and authorial manipulations, true. But as I hope I demonstrated, there's a genuine creative urge underlying all the faults of the Lee-Kirby epic-- while Conway's faux-epic is just a junk-pile composed of used furniture.