Scorpio Invasion — Alan Burt Akers

In Scorpio Assassin, Dray Prescot defied the Star Lords by saving Queen Leone from a grizzly death, and now he must answer for his disobedience. But the Star Lords argue over him and Dray is dropped accidentally in a walled garden. He is lost. Even the Star Lords don't know where he is. He knows he is on the splendid if horrific planet of Kregen, and in the continent of Loh, but nothing is familiar. He must find his way back to Makilorn, and from there to Tarankar to train an army to fight the Shanks...

Scorpio Invasion is volume forty in the saga of Dray Prescot of Earth and of Kregen, and the third book of the Lohvian Cycle.