What I'd like to see is a way for a unit to affect its attackers with an effect. For example, stabbing a lightning monster will stun the attacking unit, and wrestling with a walking rose bush would cause negative HP regen (without the defending unit having to do anything). I think the easiest way from a modder's perspective is to make this a tweak to emanations (target="attackers"). That would allow for a radius in which the effect takes place. Anything outside of the radius would also be unaffected.