The mid-to late 90's Marvel and D.C decided to fuse there characters in a series where'd they would battle to exit and re-separate back into their respective dimensions. I saw the 1st Issue of Dark Claw (Batman/Wolverine) on ebay and had to check it out.
This was a big deal for us when these came out. I have around 8/9 first issues of different titles. Did they go on for very long? Looking back, it's a nice publicity gimmick, but they couldn't have been serious.