The Yasaka Beads are a jutsu of the Mangekyo Sharingan that is used through Susano'o. Madara Uchiha is so far the most powerful known user of this technique thats been shown. Although Itachi Uchiha also used it, his seemed to be a lot weaker in power and had much less of a scale. Itachi's brother Sasuke has also been shown performing a slightly different version of this jutsu, covering the magatama with black flames. The jutsu is used by the Susanoo conjuring chakra in its hands and forming several magatama connected in some way and throwing them at the intended target.