Marv waits until #4 to introduce Nova to the shared universe, and he uses Thor to do it. It’s a good choice. Nova has still-largely-undefined powers, so having him square off against Thor shows that Nova’s abilities are probably a lot stronger than we might think. It also gives the character three issues to establish himself before trying to broaden him a bit.
There’s also a nice social commentary in issue #4, where Rich and his friends are in a soda shop and the price on the wall increases by one cent between panels. Inflation was rampant in 1976, so this was a–. Oh, it’s just a typographical error? Sorry.
Oh, and this is the first appearance of the minor villain Corruptor, yet another new villain. That’s five in four issues.
Corruptor has the power to make good guys go bad.