Elemental Affinities

Terra was formed from primordial elemental forces that lingered well past its creation. While elemental energies are strongest in the wilderness, they permeate the entire realm. Terrans recognize the main elements as water, earth, fire, and air. Other elements are either considered lesser elements (notably shadow/light, electricity, music) or as combinations of other elements (e.g. frost, storm, forest).
Every Terran is born with a connection to one, or rarely two, of the elements. This connection is referred to as an affinity. Affinities can be related to the environment of birth; after all, there is considerably more frost energy in a tundra than a desert. However, affinities cannot fully be predicted by the dominant environment, and in many cases affinities appear to be random. Furthermore, while affinities confer advantages in certain environments, these advantages are generally not very powerful. For instance, people with fire affinities are likely to have a high heat tolerance, but can still be burned if they put their hand on the stove.
The true power of affinities lies in the ability to manipulate elemental energies. An affinity for an element allows the manipulation of that element and any closely related ones. For instance, those with air affinities may be able to dabble in forest or storm manipulation to varying degrees. While it is technically possible for anyone with an affinity to use elemental manipulation, many do not learn even the basics of this, due to either lack of interest or talent. Specialization in elemental invocation, however, can provide many powerful abilities. These adepts fill many careers, though many end up as adventurers.
It is rare, but possible, for someone to change their affinity later in life. While the process is not well understood, it usually involves exposure to high levels of an alternate elemental affinity. Usually this is achieved through the trauma of surviving an extreme environment; for instance, survivors of drowning have a chance of having their natural affinity supplanted by a water affinity. Attempts to deliberately change one's affinity under more controlled circumstances have been met with limited success, and is predominantly the province of obscure academics and con artists.
Summary Water: subtypes/overlaps include storm, frost Fire: subtypes/overlaps include magma, frost Earth: subtypes/overlaps include magma, forest Air: subtypes/overlaps include forest, storm Electricity: subtypes/overlaps include storm Shadow/light: no known subtypes or overlap Music: no known subtypes or overlap