There are many ways to rig traps around your home and mines. These work to kill monsters and possibly harm or kill other players who come into your territory without permission (on servers where PvP is allowed).
There are so many ideas for cool traps that we can’t cover more than a sampling of them, but we want to get you started with a few general concepts.
Pressure Plates
Pressure Plates are critical in many traps. These items activate a charge whenever anything steps on them. A block of TNT nearby turns this into an explosive mine. But that’s pretty easy to spot. Almost anyone gets suspicious once they see TNT lying around. As an alternative, you can put the TNT below a Pressure Plate to add a layer of trickery. Consider making a Door into your house that you don’t use. Put a Pressure Plate on the inside and have Gravel or Sand and TNT below that. Anyone who enters that way will have a bad experience. Just don’t put anything valuable in that room, and make sure it’s easy to rebuild the area and the trap. This is better for a funny joke than for a serious defense.
Pistons
Pistons move blocks and make it possible to set up slightly more elaborate traps. Use Pistons for making mechanical doorways or to block passages. A Pressure Plate with Redstone channels and Pistons on the other side of a wall lets you open or close passages.
Combine this with secondary traps to make your Dungeons even deadlier. Have someone step onto a Pressure Plate, use the Pistons to block the character into a small space, and then let another Piston push aside the Stones holding back the Lava directly above them. Bye-bye!
Iron Doors
Iron Doors are excellent to pair with traps, because these items can’t be opened manually. They must be activated with a Button, Pressure Plate, Lever, etc. Because of this, you should make it easy for other players to get into your target area; leave a Pressure Plate for them to walk over so that the Door opens. Once they’re in, the Door closes automatically, and the trap has been sprung. They can’t turn around and leave without rushing to use their Pickaxe, and hopefully your TNT, Lava, or other deadly surprise is already on its way.
To make an Iron Door, use the standard Door recipe, but substitute Iron Ingots for Wood Planks.
Pits
Most characters won’t survive a fall 23 blocks down; they’ll take full damage and die even if they have full health. Unless their armor has Feather Falling, it’s Game Over.
Thus, many traps use long falls as a way to kill monsters and players. You can lure people onto blocks and tempt them to mine away, but this doesn’t work very often. Few experienced players will mine directly downward, even if a sign says “FREE LOOT INSIDE!” So, make things more interesting. Build a bridge that leads toward your base/safe area, and hide the drop with Pistons. Use a Pressure Plate to trigger a wall that pushes people into the deadly pit while they’re crossing the bridge. This still isn’t very subtle, but it sometimes works!
Many common pit traps have a top layer with a Pressure Plate, a piece of TNT underneath, and then a fall below that. This is too much work to use against monsters, but it’s reliable against human intruders.
Trapped Chests
Trapped Chests have the normal function and use of standard Chests. Double them up for extra storage, and place what you want inside. However, these Chests have a red tinge around their locks and set off a Redstone signal when they’re opened. Use this to activate TNT, Lava traps, pits, etc.
Water Suffocation Traps
Water is used to kill monsters and to funnel loot around your base. A waterway that flows down through a tunnel can be passed under a low ceiling, so that the clearance is only a single block. This traps characters and other tall monsters so that they start to suffocate. This eventually kills the enemy in question and allows their loot to drop into the water. The current carries the loot to a place deeper inside your base, where you can safely collect it. Make multiple waterways converge in one area for maximum efficiency!
Monster Holding Areas
Build a large room near your main base. Leave it lit while you’re constructing it, but destroy any Torches when you finish the entire task. Inside, create a long strip of water that flows down toward a single block. Make several of these strips converge at the same block for extra efficiency. For the final block, use a Sticky Piston and connect that to a Lever that’s somewhere safe and convenient. Or use an open Trapdoor so that monsters wander onto it and then fall. Dig a pit that’s 22 blocks deep under the Sticky Piston/Trapdoor.
Use this to capture monsters that get trapped by the water currents. Use the Lever to open the pit, or simply wait if you’re using the Trapdoor method. Build a secondary tunnel inside your base leading to the monster holding area below.
All of your foes are badly injured by the fall and die from a single hit from any decent weapon. You still get their loot and their experience.
If you don’t care about the experience, make the pit a little deeper to inflict fatal injuries. This costs you certain types of loot as well, but it’s safer if you aren’t into fighting.
Soul Sand and Ice
You gather Soul Sand in the Nether, and it slows anything that tries to walk over it. Place Ice underneath Soul Sand for an even more potent slowing effect. This is a double whammy if you create a room with any other traps, because victims can’t run away.
Monster Spawners
When you find Monster Spawners, don’t just destroy them without thinking. These items are extremely useful for creating high-quality monster farms. You can use the techniques we’ve described in and around Monster Spawners to ensure that you gather and/or kill all of the creatures they summon.
The biggest downside of making a good monster farm with Monster Spawners is that you have to stay fairly close by to get the most out of them. Monsters don’t spawn unless you’re within range.
Thus, this works really well if you stay in a particular area to mine. Otherwise, go ahead and destroy the Monster Spawner, or wall it off for now and leave a Sign to remind yourself where it is.