Uncanny X-Men. Annual. Prophetic number 13. It's an "Atlantis Attacks" crossover, as all the annuals were that year. This one, as you can see by the cover, pitted the X-Men against the Serpent Society (cool) and Mr. Jip (not cool). As you can see from the cover, it was a crappy story.
Marvel did these events in its annuals for a couple of years. I can't remember really liking any all that much. Most of the ones I read (and I only read the ones that ran in books I normally read) felt forced. If you wanted to read the entire storyline you had to buy 14 issues. Granted, that doesn't seem like a big deal now, but in 1989 that meant something. That was a commitment.
Since I didn't read every issue, and I haven't revisited what I did read since it came out, my memory of the "event" is a bit hazy. I seem to recall that it had very little to do with Atlantis attacking, but did involve Set and the Serpent Crown. It also reeked of gimmick, which annoyed me then as much as it does now. Something of this nature begs to have the big guns like the X-Men and Avengers involved, so it made sense for this to cross over into those annuals. When it was in the Daredevil annual, however, was when the stench of exploitive gimmick really assaulted the senses. Daredevil. Really?
Annuals are rare things these days. I used to look forward to them. When Marvel started doing crossovers amongst them all is when my interest started to wane. For some reason it made them feel less special. I'm sure Marvel wanted the exact opposite effect, but it failed as a company to do that.
At least the title-wide crossovers now, while still gimmicks, are more entertaining.