Indicia title is The Mighty Thor. The advertising insert adds four pages to the magazine.
This issue is a variant of Thor (Marvel, 1966 series) #421 [Direct].
There exist further variants:
Thor; Hercules; Avengers [Captain America; Quasar; She-Hulk; Sersi]; Stellaris; Hercules; Kevin Masterson; Susan Austin; Samantha Joyce; Marcy
Synopsis
Thor and the Avengers battle Stellaris. Kevin learns that his father's friend is really Hercules, and Erick Masterson comes to a decision on the custody of his child.