I have been working on nuclear bombs in minecraft, and I am finally satisfied with the results. Just restart the clock on the machine, and press the button to get a bomb to use. It will be summoned at the top of the world, and will explode everything but non-explodables in a massive radius. Anything the blast touches will be instantly killed, and anything still living will be contaminated and poisoned to death. Just don't use it anywhere within 200 blocks of your house because it will be destroyed too. Contains some special effects that I think add a nice touch to the explosion.