As Keill battles to save the planet Veynaa from destruction at the hands of an evil genius of the Deathwing, he discovers, almost too late, that there is more than one agent of the Deathwing on Veynaa.
Douglas Arthur Hill (1935–2007) was a Canadian science fiction author, editor and reviewer.
He is probably best known for his Galactic Warlord (The Last Legionary) quartet of novels, supposedly produced as the result of a challenge by a publisher to Hill's complaints about the lack of good science fiction for younger readers.
Douglas Hill. Wikipedia.