Very cool idea. I think if you made it so a die that's 1 or more above the other dealt 1 damage, and a die that is 3 or more above the other dealt 2 damage (instead of x above the other deals x damage, as you have it now), the choices you'd make of which die to match with which dic would become more interesting. You might have to experiment a little bit. But the idea has a lot of potential.