Dyadis

The Kanohi Dyadis is the Great Mask of Duality. It was forged on Spherus Magna by the Great Beings and guarded by the being Artakha until it was stolen by the Brotherhood of Makuta. Its current location is unknown and it is presumed to have been destroyed.

It is found only in the universe containing the Toa Tomari and Baragnis, and is not located in the Main Universe. Although its powers are not legendary, the mask itself posesses a similar degree of control as the Ignika.

History
While the Great Spirit Robot was being constructed, the Great Beings of this universe decided to create the Ignika and Mask of Creation. Shortly afterward, the remains of the materials used to forge them were combined together into a third mask with a strange but almost as strong power; the Dyadis. In its first stage, it appeared similar to the Ignika but with various differences, such as patterns and a mouth grill like the Vahi (which would be forged by Vakama many years later). This third mask was initially to be worn by Karzahni, however after much concern as to how he would operate after wearing this strange Kanohi, they decided it should instead be held by Artakha until the destined wearer who could manipulate the effects to their own advantage would be found.

While the Dyadis was in Artakha's care, it changed its form to that of the Avohkii, thinking of itself as its "brother", as well as a brother to the Kanohi Kraahkan. As a result of this appearance, during the Brotherhood of Makuta's attack on Artakha, the Dyadis was stolen alongside the Avohkii and the incomplete Toa Baragnis.

From this point of its history, the Dyadis has remained unheard of and unseen. It is known that at one point during its stay with the brotherhood, the Dyadis changed into the shape of the Kraahkan, which it has stayed in to this day. Teridax once believed he could use it to his advantage, however when the mask explained to him that acquiring control over a second element would also give him a second personality, Teridax threw off the mask in disgust. It is presumed destroyed by Matoran, however it is in fact still located inside a cavern which was once the home of a Makuta who was charged with holding it.

Powers and Abilities
The Dyadis, like the Ignika, is able to telepathically communicate with others and has a "mind" of its own. Unlike the Ignika but more like the Makuta, it has also demonstrated the ability to change shape, possibly being the reason as to why its current location is unknown. Also unlike the Ignika, the Dyadis' telepathic abilities are much more limited, in that it can only communicate with the wearer, and even then it is only when determining the wearer's new power. Although not confirmed, it is believed by Matoran that the Dyadis takes on the roles of the alternate personalities it forms.

The Dyadis' actual powers are basic at most; the user (wearer) upon initial placement, is granted control over any additional element of their choice, provided it is not a legendary power such as Time, Creation or life. In exchange for acquiring these powers, the wearer must agree to share their body with an alternate personality which reveals their true selves within their hearts to others. This second personality is able to take hold of the user's body at any random point, and as such can become an irritating thing. Only the destined wearer may control both personalities (to the point of combining them), while other wearers would only be able to influence their other self. If the other personality is influenced too much by a non-destined wearer or is damaged, it will detach itself from the wearer and they will lose all elemental power temporarily, only regaining their original elements after an extended period of time. At this stage the Dyadis is capable of electrocuting anyone who touches it in order to prevent itself being worn.