All Genestella have the aura known as Prana. Most will only ever learn how to use it to physically enhance themselves. However, this is not the case in terms of Stregas. Stregas are able to manipulate Prana to a higher degree of perfection than other Genestella, to the point where they can influence the physical realm outside of just simply self-strengthening. A Strega obtains the power of supernatural abilities which are usually modeled after realistic objects, such as Asseylum's fire spells taking the motif of flowers.
Currently, Stregas are known to compose 1.8% of all Genestella.