On the world I have come from, it would be considered to fall loosely into the category of thaumaturgy. [A pause.] A manipulation of energy, manifested as a variety of elementally-based spells. Fire, ice and lightning, most commonly, though others are not unknown.

[In his case, there is significantly more to it than just that, but for now he doesn't much care to mention how much more, given that it is not, precisely, relevant to the question at hand.]