Sorry I've fallen so ridiculously far behind with this topic. Thankfully it's just in time spent rather than amount to say.
Note: Main reason I've been delaying work on EM is that canon-fit retelling of Bionicle history I'm working on. Once that's complete I hope to write the Season 1 finale for the EM, and get the Shards polls up and suchnot.
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?
Mental Return -- This power is a nice idea, but why would it be a mask? I have trouble imagining that many people would want to wear that power on their faces normally. Maybe we should have a section for fan-submitted tool/artifact powers?
Emotional Override -- Firstly, that's an odd pronunciation for that spelling. Looks like Yoofo (Europe in SAE is pronounced Yurupp). But that's irrelevant to the power. My first thought is it may be too similar to the Mask of Emotion I already submitted from my Paracosmos masks. However, I can see a case made for it being separate due to the specific limitations. If you're still around (sorry again for delay *winces*) I'll let you decide if you still want it as a separate mask (say so if so, and I'll add it).
Shapeshifting -- this seems reasonable, but suggest a different name, since it involves taking on their powers too. Something like replacing, doppleganger... eh.
I think Ghost needs some clarification. It says semi-tangible energy structures, does that mean that it lets you touch others with them, but they can't touch them back?
It means partially tangible, kind of like a gel. It's not about a split effect as you describe, but rather simply behaving like a solid, but one that is somewhat intangible. Meaning if you push hard enough you could probably go through it. A Toa of Ghost could control a range of this from almost totally intangible to almost totally solid.
If you wanted to create a split-effect, you'd have to dial back the tangibility when a target tried to touch the ghost material back, as I see it, off the top of my head. But I wouldn't rule out such an automatic split effect if you want to use it that way, it's just not what I had in mind.