Vendetta, the Giant Novel

Blurb

Vendetta is a Star Trek: The Next Generation tie-in novel written by Peter David and published by Pocket Books in 1991. The book was a New York Times best-seller, peaking at #4 on the Paperback Best Sellers list in late April 1991.
The novel was subject to a dispute between Peter David and Richard Arnold, who wished the Borg character Reannon to be removed, with the logic that Borg could not be female. This was prior to a regular female Borg character, Seven of Nine, appearing in Star Trek: Voyager. Because of this, the novel was printed with a disclaimer making it explicitly apocryphal.
The plot centers around the actions of a woman named Delcara from a race which has been assimilated by the Borg, who has gone to extreme lengths to exact her revenge upon them. Delcara controls a Planet Killer, later revealed to be the finished version of the one fought by the USS Enterprise during the events of "The Doomsday Machine" episode of the original Star Trek. This Planet Killer is also 'inhabited' by the psychic impressions of its creators which exist as part of the Planet Killer's control system.