Secret Was #11-12
All about DOOM, as he gains omnipotence... but basically lounges around in his new mountain tower ("The Tower of DOOM") and thinks about invading Mephisto's realm to save his mom.
The heroes unanimously decide to attack Doom. They're instantly zapped (yeah, killed) by a big bolt from Doom. Doom's own doubt, combined with Zsaji's healing powers bring the heroes back to life. Zsaji dies after saving them all. The heroes have a big skirmish with monsters created by Klaw... then the Beyonder sneaks in and recovers his power from Doom. Zap-- that's it. We're done.
Weird thing, but it looks like one page was drawn by Arthur Adams during the big monster-fight sequence.
Fallout has the heroes constructing a grave for Zsaji. Colossus had his "moment" with her before she died, so he's heartbroken (his pants stayed on, but a modern writer might've retconned this to say it was the first time Colossus got laid).
Molecule Man was enlightened by Doom, so he picks up the "6-mile square of suburban Denver" (which looks like Brooklyn) and flies all the villains back home. Enchantress has a discussion with a Bathtub Water Spirit and finds out all about the Beyonder's past. Not much: he was the only thing in his dimension, until a "monumental event" cut a pinhole into another dimension and he began watching Earth. I think that event was tied into the creation of the Molecule Man in "Secret Wars II".
Reed builds a device that can send everybody back home, with three more developments:
1- Thing gets She-Hulk to replace him in the FF. He stays behind since he can now control his changes into the Thing. Reed lets him keep the transporter device for whenever he gets bored of Battleworld. I have most of these issues of "The Thing", but I honestly don't remember how it played out. Reed mentions that there's a suspicious and/or depressing reason for Thing's control, but I forget what it was. Something to do with the whole "wish fulfillment" thing and how Battleworld seemed to fit the heroes and villains, perfectly (Spidey noticing all the web-slinging props, Storm easily controlling the weather, Cap re-forming his shield from nothing, etc.)
2- Lockheed returns with a female dragon. The female dragon flies in and gets transported back with the X-men. It eventually grew to gigantic size and rampaged Japan. Seriously. Rogue, Prof.X and Storm also got new costumes. Rogue's has a totally 80's mini-skirt, so I think this was the end of "bull dyke hoodie Rogue".
3- Enchantress zaps the Lizard back to Dr. Curt Connors. He hangs out and goes home with Spider-Man. Spidey realized he used the wrong costume machine... but just shrugs it off.
Oh golly--- this series was a lot of fun! Once you start reading it, it gets in your head and you can't stop thinking about it. It's a Big Dumb Superhero Story, but darn if it isn't entertaining and just overall FUN. I've always liked mass team-ups, which explains why I dig the All-Star Game and have fond memories of junk like "Yogi's Ark".
This project was started as a merchandising and licensing gimmick, aimed at kids. But "big kids" loved this series, too. They thought they weren't supposed to, but they did. It's very hard to find a Comic Nerd who hates this series (well... maybe those who were REALLY into Sandman or Shade and feel this kind of drivel is beneath their intellect).
Doom is awesome and this might very well be one of his best stories. After issue 9, he basically takes over the spotlight. When the craptastic "Secret Wars II" rolls around, I don't think Doom is there... and that's a shame. I think he had a part in the FF-only "Secret Wars III", where it was revealed the Beyonder was a rogue Cosmic Cube or something. That'd require I re-read my 1988 FF books and I'm not up for that.