Oni Mask of Vengeance

The Oni Mask of Vengeance is one of the three Oni Masks. When worn, it will turn the user into a master swordsman with two additional arms.

History
At some point in time, the three Oni Masks were created in the Realm of the Oni and the Dragon by the Oni. They would eventually end up in the realm of Ninjago through unknown means, with the Oni Mask of Vengeance falling into the possession of Cyrus Borg, who hid the mask within a secret compartment within Borg Tower.