Playing PVP and want to get a little revenge, or just have the thrill of killing your opponent? Well if so, this is the instructable for you.
Step 1: Layout
First dig a 2 block deep 2 by 4 hole. Then place two diamond ore blocks at the far end of your hole. Now dig an extension of the hole under your diamonds.(The hole is now 2 by 5)
Step 2: Levers, Redstone, and TNT
Now, place two levers below the diamonds switched to the on position, then the redstone is powered. (The levers are switched to the on position because redstone torches give off a redstone signal, meaning they will ignite the TNT. When a redstone torch receives a redstone signal, it turns off. So, with the levers to the on position, when either diamond is mined, the lever is destroyed, thus the redstone signal turns off, and the redstone torch turns on, igniting the TNT).
Dig one block beside each lever, then place redstone dust on them. Then dig the two blocks behind the sandstone with the redstone on it, and replace the top block with a slab, so the redstone can travel down. Now place two redstone torches on the blocks directly behind the redstone dust, facing inward. You should now fill the remaining four blocks behind the torches with TNT.
Step 3: The Results
To finish it up, cover the hole with stone (or whatever block best fits your surroundings). Also place stone over your slabs. Your deadly trap is now set and ready for any unsuspecting miners who pass by.