King Kobold Revived - Christopher Stasheff - Bog

A MYSTERIOUS INVASION FROM BEYOND SPACE AND TIME.
Surprise raids are ravaging the kingdom of Gramarye. Longships filled with Vikings wielding the magical, paralyzing Evil Eye plunder, kill, and burn whole villages, then disappear back into the dark seas. But where did this enemy, and their mysterious god-king Kobold, even come from?
For Gramarye exists not in the past, but the far future: a lost colony planet that's reverted to a simple medieval lifestyle... complete with fearing and persecuting the witches and warlocks among them, people born with natural psionic abilities (and the only known espers in the universe). This island kingdom represents the only sentient life on the planet... or so they thought, before the brutal marauders appeared.
Rod Gallowglass is an agent of an interplanetary government, stationed on the recently rediscovered Gramarye to protect its precious psionic community, and gradually guide the kingdom toward integration and membership in the galactic union. A modern man of science and technology, the locals mistake him for a powerful warlock (despite his claims he isn't). Now King Tuan and his subjects look to the "High Warlock" to help them repel the invaders.
Can the High Warlock not only drive the barbarians back into the sea, but deduce where they came from, why they're attacking, and how to end their raids forever? If you're intrigued by this blend of swords, sorcery, and science, you'll enjoy reading King Kobold Revived.