Fanaticism can be just as dangerous as fire. Spreading like fire, it could spark rebellion and could lead towards violence. As a way to curb devotion to the abstract, king Hareth of Garilroot asked his Mages to come up with a solution for those too invested in an ideal.
The Earthblood Warrens are a series of caverns in which dwell men who live around the Earthblood Vein, a river of magma. They use the magma from the Earthblood Vein to warm and light their homes and cook their food. The Warrens are several miles long, stretching along the banks of the Earthblood Vein, and since nobody wants to walk that far, the Earthbloodmen capture large, magma-swimming serpents, which they train and ride.