Deathmate

Solar and Void are in the foreground

This is an extremely infamous comic crossover. Why? It helped cause the 1996 collapse of the comic book industry.
Premise
I found it impossible to find a summary of the complete series. I all I could find was the basic the premise. So, that's what I'll talk about.
Void (from Image Comics) and Solar (from Valiant Comics) met each other and became lovers. However, this somehow "begins to unravel the strands of time, creating an Alternate Universe where Image and Valiant characters exist side by side". Somehow, this will also result in the destruction in the new universe.
Issues
There was six main issues of the comic. Three issues were produced by each company. The only two issues that had to be read in order were the Prologue (which had to be read first) and Epilogue (which had to be read last). The remaing issues take place in-between the latter two, but at the same time. As such, the issues don't have numbers, but colors since they were meant for it to be possible to read the middle issues in any order. Valiant produced issue Prologue, Yellow and Blue. Image produced issues Black, Red and Epilogue.
Problems and Aftermath
Problems popped almost immediately. The basic premise was weak. Jim Valentino, Erik Larsen and Todd McFarlane, despite making up half the creative force at Image, didn't work on the venture. Al Simmons only had a minor role in working on the comic. The creative crew from each company knew nothing about the other company's characters leading to tons of out-of-character moments. Image's over-the-top style didn't work too well for the comic. While the Valiant's issues were publish on schedule, Image's issue arrived late. Even then, Bob Layton had to fly to LA and refuse to leave Rob's doorstep until he finished his portion of the comic. It took Image over six months (despite what the cover dates) to finish the crossover. Because interest died for crossover in the intervening time, retailers had tons of unsellable comics. This is ultimately juggernauted into the 1996 collapse of the comic industry and contributed to the end of Valiant Comics. So the line, "Their love will end worlds!" (used in the advertising for the crossover), became darkly ironic.
References:
http://en.wikipedia.org/wiki/Deathmate
http://tvtropes.org/pmwiki/pmwiki.php/ComicBook/DeathMate?from=Main.DeathMate
http://majorspoilers.com/2013/06/09/retro-review-deathmate-black/