Havilfar Cycle Series by Alan Burt Akers, Kenneth Bulmer

The sixth book of the Dray Prescot series. Would Dray Prescot be able to remain a prince of proud Vallia or become just another human victim of the hunters and manhounds of the mysterious Southern Continent? For that was the enigmatic fate that the Star Lords had suddenly confronted him with. They wanted someone freed from the terrified pack of human prey among whom Prescot found himself. But who it was and how it was to be done, they left to him to work out...

The seventh book of the Dray Prescot series.Never a man to leave something half done, Dray Prescot knew his task on the mysterious continent of Havilfar was far from completed. There were cruel conquerors to be overthrown, there was pursuit of the manhounds and their masters, and there was the dreaded arena. Could he survive the life of a gladiator against the killers and monsters of a spoiled queen -- while the Star Lords waited for his mission to continue?

The eighth book of the Dray Prescot series. Dray Prescot, the Earthman who had been brought across interstellar space as the tool of the mysterious Star Lords, confronted his most baffling task while he was a hunted and harried wanderer of the continent of Havilfar. That task was to discover the means by which the aircraft of that continent's most advanced civilization operated... moreThe eighth book of the Dray Prescot series. Dray Prescot, the Earthman who had been brought across interstellar space as the tool of the mysterious Star Lords, confronted his most baffling task while he was a hunted and harried wanderer of the continent of Havilfar. That task was to discover the means by which the aircraft of that continent's most advanced civilization operated. Prescot is no scientist, but fulfill his task he must or he would never return to the princess and homeland he had won. So, for Dray Prescot there was but one course -- with a whole continent against him, with time itself conspiring to balk him, the secrets of an unknown science must be made his... less

The ninth book of the Dray Prescot series. The problem with being a spy is that you have to make friends with the enemy. Dray Prescot, Earthman, who had become prince of Vallia, was the kind of man who always stood by his friends. So in his quest to learn the war secrets of Hamal, empire of the aircraft-makers, Dray found himself not only becoming comrade to some of its greatest warriors but of championing the very life of its cruelly beautiful queen... moreThe ninth book of the Dray Prescot series. The problem with being a spy is that you have to make friends with the enemy. Dray Prescot, Earthman, who had become prince of Vallia, was the kind of man who always stood by his friends. So in his quest to learn the war secrets of Hamal, empire of the aircraft-makers, Dray found himself not only becoming comrade to some of its greatest warriors but of championing the very life of its cruelly beautiful queen. Although Dray's devotion to his glorious princess Delia never flagged, his mission, and his life, was perilously balanced upon the razor-edged blades of loyalty versus duty... less

SEA WOLVES OF SCORPIOFor a brief but wonderful moment it seemed as if Dray Prescot was on the road to victory, for he was aboard a Vallian ship bound for home with the secret of Vallia's enemies in his possession... moreSEA WOLVES OF SCORPIOFor a brief but wonderful moment it seemed as if Dray Prescot was on the road to victory, for he was aboard a Vallian ship bound for home with the secret of Vallia's enemies in his possession. But Dray, the Earthman sent to the planet Kregen of the double-star Antares in Scorpio, had not fulfilled the mission of the unseen Star Lords, and until he did there could be no escape from peril! And peril came, in the form of hideous sea raiders, in the sharp edges of the dueling blades of a swordsman enemy, and in the horrid rites of the underground cult of the Silver Leem. Dray Prescot's saga has been aclaimed as the best planetary adventure series since Burroughs stopped writing about Barsoom, and a legion of devoted readers will find that Avenger of Antares holds high the standard. less

Kregen! That marvelous world circling the double-star Antares in the Constellation Scorpio has been the scene of many an exciting event as its myriad human and non-human races struggle with each other for ascendency. But for Dray Prescot, Earthman and Prince of Vallia, all of the electrifying aspects of his adventurous life on Kregen were to climax when the armies of Havilfar made their move toward his adopted homeland before he had fully solved the secret of their mysterious air fleets... moreKregen! That marvelous world circling the double-star Antares in the Constellation Scorpio has been the scene of many an exciting event as its myriad human and non-human races struggle with each other for ascendency. But for Dray Prescot, Earthman and Prince of Vallia, all of the electrifying aspects of his adventurous life on Kregen were to climax when the armies of Havilfar made their move toward his adopted homeland before he had fully solved the secret of their mysterious air fleets. Armada of Antares is the culmination of all his experiences on Kregen so far -- a peril-pitched novel, complete in itself, of an alien world stirred up to a life-or-death frenzy. less