Dr. Doom wants to get the cosmic cube from AIM to save his face. Yes, he wants omnipotence because you can’t find a good plastic surgeon in Latveria. And there’s MODOK.
There’ s not much of a reason for Sub-Mariner to be in this story, but they include him because it’s his book and he’s lost his memory, anyway, due to his daddy issues. (Remember, Tiger Shark killed his father in the last story?)
Namor tends to get Amnesia. This was established way back when Human Torch found him as a bearded homeless man.
Creators: Gerry Conway and Gene Colan