Uncanny X-Men #274 is, I think, the first issue to be narrated by Magneto. Having rescued Rogue in #269, he's gone to the Savage Land with her for a team-up with Ka-Zar and a show-down with Zaladane, who is using her magnetic powers in a way that might threaten the Earth. He encounters the mess of a much earlier expedition of his to the area, in the form of the Savage Land Mutates. Zaladane has also come to the attention of Nick Fury and SHIELD. Unusually they team up, despite the reservation of Colonel Semyanov, whose son was killed when Magneto destroyed the Leningrad
Magneto is introspective and moody in a way we've never quite seen before. The flashback to the firing squad is particularly effective - and will form a centrepoint of Pak's Magneto: Testament miniseries 17 years from now. He disassociates himself from his earlier "insane" actions, comparing them to Zaladane's now, but also is unable to apologise or take responsibility for them - the Leningrad did nuke him, yes, but he was blackmailing the world with demands to be made dictator. Another new wrinkle is Rogue's claim that Magneto hates Russians for the death of his daughter Anya, which is compared to Semyanov's vendetta. It unfolds unsurprisingly, Semyanov sells Magneto out to Zaladane, and then Fury/Magneto/Rogue win anyway. What is Magneto like in victory, though? Not, it turns out, magnanimous. Indeed, he declares his period of reform over: he needs to protect mutants (but without being a cackler himself), and says that a "kindler, gentler Magneto" cannot save them. He vamooses, presumably to take up villainry once more.
This arc introduces the idea of Rogneto. In a fairly creepy way, it has to be said, Magneto is perving on a Rogue who is not her usual self and clearly lacking in judgement (why are they killing people she asks, aren't they supposed to be the good guys? Uh No.) Thankfully the matter is dropped and then never referenced again.
In our other plot, for some convoluted reason the X-Men (Storm, Wolverine, Banshee Jubilee, Forge and Gambit) were teleported away from Earth by Lila Cheney to the eternal Shi'ar civil war. Deathbird is empress right now, and the rebels the Starjammers (Corsair, who just happens to be Cyclops's dad) are fighting to reinstate her sister Lilandra to her rightful place on the throne. If I were them I'd be trying to undermine the entire system of Imperial rule, but perhaps they are expecting plum ministerial positions under the new regime... at least until she gets turfed out again.) The war is not going well for Deathbird, largely because Lilandra's consort is a highly powerful telepath: Charles Xavier, who also happens to be the founder of the X-Men! But Xavier is possibly secretly evil and doing a bit of genocide on the side. Except then it turns out he is a Skrull, and so are the rest of the Starjammers! And they've got the real Xavier kidnapped! And then they free the real Xavier! And then they defeat the Skrulls! And then Lilandra and Deathbird actually do the "our division caused us to be weak against our enemies, let's make up" dance.
At the end, Storm infodumps enough of the disasters to have happened to the X-Men since Xavier left, and he learns of the rise of the Shadow King. Xavier agrees to come back with them, setting the stage for our next arc, Claremont's penultimate hurrah.
I believe this is the first intrusion of the Skrulls into the X-verse; certainly it's the first time I've written about them on the blog (apart from a passing reference to John the Skrull). The Skrulls are a race of alien shape-shifters originally introduced as villains in Fantastic Four #2. In that very first story a small advance party are brainwashed into thinking themselves cows. They go on to be frequent antagonists in Marvel: a Super-Skrull, Kl'rt, who combines the powers of the Fantastic Four, is introduced in FF #18 (it's this job that Xavin out of Runaways is training for), and fight the Kree, another alien race, in the pages of Avengers; and their latest invasion of Earth was the topic of the Secret Invasion crossover.
All these alien races were made up independently: the Skrulls in those very early days of the Marvel Silver Age; the Kree a bit later, in FF #65, and then the Shi'ar in the 1970s in these very pages. These, then are the Big Three Marvel Alien Species. Rather than anyone having sat down and worked this out, this is worldbuilding through crossover, things in a shared universe being patched together to form a galactic quilt. But that's just a larger-scale version of a continuity that allows Doctor Strange and Iron Man to co-exist; throw everything at a particularly sticky wall and watch it not going anywhere. Because... indeed, it's not going anywhere. It's rare for cosmic dynastic stories to have a point: it's just The Decline and Fall of the Roman Empire on repeat. If I wanted that, I'd just read Foundation again.