The Ichor Machine

The ichor machine, or third heart, is a type of artificial heart used to overcome the natural limitations of a typical magus. (As explained elsewhere, a magus' magical capacity is limited by the conflict between her first and second hearts.) The creation and use of such a machine is not the same thing as the transplant of a first heart from one human into another. Rather, the ichor machine is a construct mainly consisting of opals and the heart of another human. They are ideally supplements, not replacements.

The high demand for ichor machines makes finding a willing donor unlikely, and only the freshest or well-preserved hearts are suitable. (Some find it eerie how easily it fits into and embeds itself within the human chest.) Unsurprisingly, this has also driven a market for the unethical acquisition of human hearts as well.

The advantage of an ichor machine is that it fuses the strengths of the first and second hearts into one being. There is no conflict between the parts of an ichor machine, and thus no upper limit to a magus' power besides how much water (or blood) she consumes. A magus with an ichor machine can perform incredible feats that would take most normal magi years of practice to accomplish - as long as they have enough water or blood. A magus with an ichor machine suffers a constant thirst that does not just pester them, but progressively dominates their minds.