Isanga denotes the deadly killing-sorcery of the Mekeo together with the lethal spirit-power that carries it. It is one of the 'gifts' that A'aisa left to humankind and is deployed by the hereditary death-dealing sorcerer against victims marked out for punishment or vengeance. As with the other Mekeo spirit-terms, isanga names a power and a class of malign agency rather than a single individuated being; the boundary between isanga and the sorcerer's faifai familiars is drawn differently by different accounts.