Too bad "Heal" can't be used offensively

I'm not much of a poster on these forums and am just now actually enjoying a game since the very beginning of Elemental.  I am very pleased with how this game is coming.  One idea that has occured to me is to combine the heal with the wither spells.  In my line of thinking to heal a body, one must take that energy from somewhere else.  I would like to see, perhaps if I can learn how to mod) a healing spell that TAKES the same amount of hit points from an opposing army or character.  This way it can be offensive as well as defensive.