Minecraft wiki entry for Enderman_farming, associated text: To use the trap, stand on the pillar, grab a sword and look at an enderman, causing it to rush toward the player and fall into the pit. Activate the lever to extend the pistons. Wait a few moments and deactivate the lever. The enderman should be weakened by having its head smashed and the player can kill it with one strike. An upgrade is placing pressure plates (wooden for testing, so the player can activate the trap with an item, and stone for the enderman) at the bottom of the pit and rigging redstone into an AND Gate. The lever primes the trap and the enderman touching the pressure plates activates the pistons.