Got this issue (or another copy of it!) for 12 cents, and even on that sliding scale...it's still not very good. From 1991, Avengers Annual #20, "A Storm in Subterranea part 1: Of Moles and Mutates" Story by Roy and Dann Thomas, pencils by Kevin West, inks by Fred Fredericks.
This issue's lineup of Avengers seems odd to me, like it was the roster for about 20 minutes in the 90's: maybe it was longer, but I don't recollect seeing this particular grouping again! It's also surprisingly overpowered for an Avengers roster. Hercules had even been powered down at that point, but the Eternal Sersi more than makes up for that. There was also Quasar, in his masked costume: if you read his comic, that outfit was a retroactive addition to the timeline; but it was also pretty short-lived. There's the (white, emotionless) Vision; She-Hulk, probationary members Sandman and Rage; and Captain America and Black Widow. And the Widow has a white costume, for some reason. (Coloring failure? I thought her outfit at the time was more dark grey in the coloring of the era.)
This was the kickoff for Subterranean Wars, and tries to set up Brutus as the big-bad, since he has the usual underground rulers Tyrannus, Grotesk, and the Mole Man on the run. Instead, the effect is more like "Oooh, someone scared the Mole Man? Why, they must be hardcore!" Actually, as far as guys living underground, Moley seems pretty reasonable: after getting trounced repeatedly trying to take over the world, he's somewhat resigned to keeping his little Moloid subjects and assorted Kirby monsters safe. He's certainly more personable than Tyrannus or Grotesk. (That might even be Grotesk II, I think the original died hassling the original X-Men?)
While Cap and Widow tag out, ostensibly to get the Fantastic Four in on this thing (Spoiler: they don't!) the rest of the Avengers are somehow captured, where they would spend most of the rest of this crossover. Previously, we saw Namor was about to try and get them, but got sidetracked. Oof, we're actually over halfway through this thing: we took a peek at the Hulk's chapter years ago, without mentioning Subterranean Wars at all...time to update the tags!