Jecca raised her hand and "Most spells are listed by their incantation, with their vernacular name in parentheses, when known. Some spells have no known incantation—the only canonical reference is by an informal name. It is possible to omit shouting the incantation aloud in order to gain a tactical advantage when dueling; such spells can generally only be identified by their effects. As most people, including skilled adults, appear to generally use incantations, saying them aloud seems generally preferable in terms of efficacy. "