So I have some mask ideas:
Kanohi Zetax, the Mask of Mental Return
Allows the user to "return," so-to-speak, to a past version of their mind. The effect of the use of this mask is permanent. The user forgets everything from the "return-point" on. Basic knowledge of the five w's are still retained. Some beings could use this to carve out a new life for themselves.
An example of use would be a toa (Canon example Lesovikk) who is very traumatized by event X. If they had this mask, they could "erase" all memories form that moment on.
Kanohi Eupho (Ay-foe), the Mask of Emotional Override
Allows the user to "implant" their emotions into another being or beings ("Victim(s)"). The mask is always on at a low level. Ex: a very angry makuta could make a toa feel nothing but wrath.
Kanohi Borili, the Mask of Shapeshifting
Allows the user to temporarily completely shapeshift into any living being, object, or thing (toa, rock, vahki, respectively), given that they're on the planet at the time of shapeshifting. The kanohi also allows the user to temporarily gain access of the "victim's" powers and element, overriding the user's powers and element. The kanohi also changes shape to match the being's mask, but it doesn't change power. Basically, if the being exists on the planet at the time of use, it can be shapeshifted into.
-Mass of "victim" cannot exceed 1.5 times that of user
-The victim cannot be the only one of its kind or the last of its species
-Size alteration and reconstitution/mutation of existing beings is inhibited by the mask
-The mask takes about a day to "recharge" the life energy used to shapeshift and/or change size.
--Shapeshifting back does not take life energy and can therefore be done in the same day
I don't know. I tried to not make the mask too overpowered. Also, can there theoretically be a failsafe in the mask that prevents conjunction with an Inakko and a Kenalgi?