Another sample capx --
Pick enemies
Filter function in "move-able area" could get attack-able (in this capx, the attack range is 2 (tiles)) enemy instances.
Just put target chess.uid at "action:Append filter result". Then pick chess from instance group after doing "action:Get moveable area".
More over, user could pick target chess with more conditions like checking the HP (saved in instance variables) , or something else.
PS. user need to update board plugin to open this sample capx.