Into the Labyrinth by Margaret Weis & Tracy Hickman

Into the Labyrinth - Margaret Weis, Tracy Hickman

This is the 6th novel in the Death Gate Cycle and won't make much sense unless you have read the previous 5 books.  Into the Labyrinth continues the action packed story of Haplo, Alfred, and Dog, who have been stranded in the deadly Labyrinth; and of Xar who is hell-bent on conquering the world via zombie apocalypse.