A guillotine was a medival device used for executions.Since the 1.4 update, they have added anvils for repairing tools and combining enchantments. An interesting trait they have is that they are affected by gravity and damage any mob unlucky enough to be under them. Using redstone, I have made a device that retracts a piston, dropping an anvil from a height of 140 blocks! A two or three block high mob is needed and this works best in creative. In case you are in survival, there are chests provided with eggs and blocks needed for golems. Note: Iron golems may need more than one anvil to kill them.

Additional Notes

Do not mind the name of the file, I made this world long before deciding to upload it.