The KanohiRua was the Great Mask of Wisdom. It contained and gave its user the powers of the Miru, Kaukau, and Akaku.
These various mask powers could be activated individually or simultaneously by their user. A Rua could be formed by merging a Miru, Kaukau, and Akaku together. The mask appeared as a silver Miru. If a Rua were taken off its Toa Kaita, it would exist only as long as the Kaita existed. Only Toa Kaita could form Great Rua. However, it was not possible to create a Noble Rua.