I am trying to make a minecraft war map. I want everybody to have land mines they can place. I know that I can test for a pressure plate being stepped on and have a comparator coming out leading to a command block that summons tnt. The problems I am having are that I don't know how to test for a block that is anywhere in the world. I only can test for a block at specific coordinates. Also I don't know how to summon tnt relative to the pressure plate.