Web of the Witch World

Fourth Ace edition, with cover art by Davis Meltzer. Simon Tregarth, whose Earthly prowess had won him a throne and a witch-wife in an alien world, knew that both triumphs were precarious as long as the invaders of Kolder held a foothold on the planet. These not-quite-human invaders, like Simon, had come to the witch world from another existence. Somewhere, they were building with their super-science the means of enslaving an entire world.