Instructions
Load "Minecraft" and enter a game server.
Select the type of trap you wish to use and select the location for it. A TNT trap is very destructive and will easily kill intruders, but it can also damage your own structure. An Arrow trap is less effective but more controllable.
Place a TNT or Arrow dispenser in the location to kill the intruder. If it is TNT trap, dig a trench at least two blocks deep. Place the TNT into the trench and cover it with dirt or other material. Dig a tunnel leading away from the TNT. If you are using an Arrow dispenser, place it in front of the area and determine the direction you want it to shoot.
Place a Redstone torch on the back of a block. Put the block in a strategic location which will make any intruder think he has to destroy it to get into your structure. The block, once destroyed, will act as the trigger for your trap.
Set down a trail of Redstone dust from the Redstone torch block leading toward either the Arrow dispenser or TNT blocks. Do not connect the trail to the device just yet.
Place another Redstone torch down on the trail of Redstone dust. This will deactivate the Redstone dust so that you can safely connect it to the trap device. Connect the Redstone dust trail to the trap device. If you are using a dispenser, load it with arrows.
Cover the Redstone dust path with blocks so that it is not easily seen by other players. When the block from Step 3 is destroyed, it will trigger the stealthy trap and kill any intruder.