A mostly desert world where the only hospitable land is at the poles of the world. Ringed by mountains, the poles are the only areas of known surface water and arable land. The culture that lives there dominates agriculture and is imperialistic. There are other cultures that live in the underground regions of the planet, protected from the harsh conditions of the surface. They are more nomadic and know how to travel the surface and get to the remote regions of the planet. They are more technologically advanced, though they rely on the pole society for fresh foods.
Magical ability is seen negatively, like a defect or an illness or an inherent corruption. There is also a disease that will drive the victim slowly mad, like rabies or that fungal infection that makes zombie ants. No one is quite sure where it comes from except that only those who travel the surface of the planet or dig too far away from the poles get it. There is no readily known cure. Infection is a death sentence at best.
Inspired by Dune and a tumblr post about dead gods being like a whale fall in the ocean (https://transmechanicus.tumblr.com/post/670438489225150464/i-love-the-idea-of-dead-gods-not-in-the-sense-of).