I checked around to see if any other cards were similar to this idea, didn't see any.
The basic concept for the type of shield here is one that is more effective against small numbers of creatures than larger numbers. The shield achieves this by blocking a set number of attacks per turn, similar in style to the bonewall, except instead of a running total that can be increased, it is set to a certain amount each turn.
So I see a card that would be something like:
Decoy Shield
Costs 5[
?] Feels like entropy fits best, although name could be easily changed if another element would work better with it.
Decoys: You take no damage from the first 3 attacks per turn. (4 or 5 if upped)
Works well against low-count high-damage creatures
Does poorly against creature spams and adrenaline.
Can be neutralized by playing weak creatures first and then higher-damage creatures, although CC could mess around with a strategy like that.
