It is taken for granted that medical technologies will advance apace in the future, permitting rapid healing and perhaps even shaping of the human body. This submission is to provide possible flavors for that medicine to come in.
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.