Legacy of Doom was a proposed novel to be written by Margaret Weis. It was apparently supposed to be a sequel to Exiles of the Force and The Heart of the Jedi. It was canceled in 1995 due to a difference of opinion.
In 2016, Joseph Bongiorno intended to publish Legacy of Doom on his website, "The Star Wars Expanded Universe Timeline." He managed to contact Margaret Weis, who let him know what the fate of the story was, and how it ended up not getting published: "I no longer have the book. I saw no reason to keep it and it was on a computer that I have long since retired. My story is that I had only a limited window of time in which to write that book, as I had other book commitments at the time. I handed in the book, but the people at Lucasfilm kept changing their minds about what they wanted and having me do rewrite after rewrite. At last I told them time was up, this was getting too frustrating and I moved on."