The lowest points don't get affected during a clash? Because these devices are deep into the die. The fields are affted because they are the outside of the die. So where the outlines of the devices hit the other die, they are transferred to the other die. On a very strong clash you will see letters. But the highest coin devices, are the lowest die devices. (Dies are a negative of a coin)

Note the light direction this image. The light is from the top and the dark area on the top of the shield tell us that it is deeper into the die.