Fall-Traps will trick mobs and players to fall into pits... how big the pit is will determine if they die. Combined with lava these are the deadliest weapons in your arsenal. They can be created to look like smooth stone, cobblestone, sand or dirt. When walked over they turn into a stick and the player or mob falls in. Once a fall trap has been tripped it has to be replaced.
3 sand/cobble/smoothstone/dirt and 3 Sticks