Issue: Avengers # 10
Writer: Stan Lee
Artist: Don Heck
Publication Date: November 1964
So, Immortus is the new villain that stops by to chat with the Masters of Evil. His first move is choosing Paul Bunyan to fight with Executioner. This is how he chooses to display his power. The Masters of Evil are impressed, which is a good indicator that they don't really have a good proof of concept for their little villain organization.
Anyways, the Masters of Evil want Immortus to kill the Avengers. Naturally, this leads the Avengers into fighting each other. I don't know how many more hero vs. hero stories I can take.
The team then faces off against a bunch of mythical figures of ages past, such as Goliath and Merlin. Thor does fight Hercules, so there's that. Enchantress decides to move everything back in time a week to before the team encounters Immortus, so it's as if the fight never was. If she's this powerful, shouldn't she be able to take down the Avengers single-handed?
Cap poses for the pinup
Next: Fantastic Four # 32