“...And you, Human, must follow our words, lest we summon up every curse that lies buried beneath these sands and pour them upon you and your children, and their children, and in turn their children, for so many generations that your blood will surely never survive.”
Somehow, someway, a band of gnomes learns how to be ninjas. In fine gnomish style, they open an academy to teach this art to other gnomes. Wacky Hijinks ensue. Or the gnomes become some of the finest assassins in the land. Or both.