You could have it use the effect in a 3x3 area with a hole in the center.
Like this:
[y] [y] [y]
[y] [_] [y]
[y] [y] [y]
[ ] Represents a creature slot, y represents the affected slots.
hmmmm. even using
that way, the board is not often filled to those slots, and when they are, it usually takes a lot to get to that point, nor for when it is filled is it the right way for what i'm thinking. i'll think about it some more, but i'm not sure the idea will work... unless i start thinking of circular effects.
There could be de/buffs, more of other effects already in the game, making all in the range change to an element,
gah!