So a symmetrically Eye or brain is called for IHMO. Could even be as simple as [backward "n"]"n".
I understand that mine is too basic for a representation, at least consider a grey mark on the scale since it hasn't been used yet in the game.
about that eye thing Assuming we are going to let the community help us out:
the eye is an already take idea by pokemon which is essentially the representation of a variation of the same concept we are doing, I doubt people will deem it as "original":
Despite this one not being involved directly in the game mechanics, It is still of psychic/mind essence which interferes with the card game:
An eye is a good idea imo, but I think in terms of originality related with "Mind", It is lacking IMHO.
I propose an "Indirect" symbolism of mind, meaning an indirect, symmetric representation such as
or
.