This Instructable will show you how to make a skeleton defense system. This is a system meant to keep enemy players away while you are AFK or off the server / LAN world altogether. As you can see I built this in creative so just remember that the grass blocks would be ground level in survival. There will be a video demonstration at the end if you want to see it working. Lets begin...

NOTE:As shown in the second picture, there are blocks that you might not think are in vanilla minecraft. They actually are called barrier blocks and can be given to players using a command. (I will post that command and any other I used at the end). So if it looks like there is floating water at some parts, I am using those to keep it there. So when you make this, make sure that is is closed off at the parts that use water.

Step 1: Building Materials

To build this you will need

- To find one skeleton spawner (In case you're wondering: DO NOT DESTROY IT!!)

- Fences (you could use other blocks, but I found fences to work a little better.)

- Sticky Pistons

- Water

- Redstone (repeaters, redstone, levers, and stone pressure plates)

- One building block of you choice

- Signs

Step 2: Starting the Wall

The first part is to start the outer wall; the key thing to remember with this is make the length an odd number for the best results. In the case of the one above, it is 19 long and 5 wide. The length does not matter, but the width should always be 5 blocks for the best results. Make sure the area around were you are going to build this is flat for the best results.

Step 3: The Delivery System

This is where the spawner comes in. In this case, I used a command block with a command to summon skeletons instead of a spawner. When building the room, you want it to be 7 blocks long by about 5 blocks max. This will ensure that the water pushes them all the way across the room to the delivery system. After constructing the room around the spawner, the next step is to put one water block in the opposite corner of the room where you want the delivery system located (as shown in the 2nd and 3rd picture).

Step 4: Delivery System Continued

Next, you put a hole in the ceiling above the opposite corner. Then you will make a chute up to ground level as shown in the the 1st picture. Next you will want to put a sign on every other block starting from the block right above the ground up until the top of the chute or one below the top depending on how may blocks high the chute is. Finally, to finish the delivery system, place water between the signs.

Step 5: Skeleton Pens

To build the skeleton pens, I used fences since it is the easiest to keep them in with. You are going to want to put the fences on every other block, leaving a one block space between each individual pen. Also, you are going to want to make the fences 2 deep so there is room for the skeletons and 2 high so the skeletons don't get on top of them. After you have completed that, you want to put a stone pressure plate between the fences on the block closest to the wall. Finally put a hole behind each of the pressure plates.

NOTE: You must use stone pressure plates or else when the skeletons die another skeleton will not be able to get into the pen.

Step 6: Entrapment System

To build the system to keep the skeletons inside their pens put a sticky piston one block under the hole. Then proceed to put a fence on top of each of the pistons. Next, put redstone directly under the pressure plate and level with the piston. Finally, test it out by standing on the pressure plate. If the fence is pushed into place by the piston you are good.

Step 7: The Distribution System

The purpose of the distribution system is to distribute the skeletons into their pens. First you are going to want to build a back wall that is 3 blocks high. After that, put one water block at the very top of the chute one block above ground level. At the end of the stream, if you need to make it go farther, add one sign directly above the very last water block followed by one right in front of it. Then place a water block in between the two signs. Continue the water stream until the end of the wall; if it goes off the side, that is fine for the time being.

Step 8: Collection System

You might be asking yourself by now what happens to the leftover skeleton after the pens are filled. Well, that's where the collection system / mob grinder comes in. The first thing to do for this is stop the water flow so the mobs will actually fall down into our collection system. In the first picture you can see that all I did to stop it was put a sign under the water flow and one in front of it. This should stop it completely. Now you have to remove the fences at the end because if you don't the skeletons will just sit at the end forever. So replace the fences with a two block high wall as seen in picture 2. Finally, make a chute for the skeletons to fall down into.

Step 9: Protection System

At this point you might be asking yourself how you get in and out with out being shot. Well that is where the protection system comes in. This is pretty easy to make. All you have to do is make another line of blocks above the first wall. Make sure there is a one block gap between the blocks. Then simply place sticky pistons above the wall you just made. Make sure the pistons are facing downwards so they push the blocks towards the first wall. Finally, place one more row of blocks above the pistons and lay down a redstone wire connected to a lever on top of that row. Make sure to use repeaters as necessary.

NOTE: This step is not actually necessary, there are other solutions to the problem of getting shot while exiting/entering. You could have your door out of the skeleton's view, or even have an underground entrance. This design is the best if you have the resources, though.

Step 10: The Roof

The last thing to do is make a roof above the pens and everything else so the skeletons don't burn up in the sun. I would recommend you make sure it goes over the distribution system so they can't get out. And that is the final step. You now have a skeleton defense system!! Enjoy!!

Step 11: Video Demonstration

Step 12: Commands

As promised here is the list of command that I used in the making of this project.

Barriers - /give minecraft:barrier

Summon Skeleton - /summon skeleton

If you liked this build at all hit the favorite button and I will try to get more minecraft stuff to you. Also if you have any question over how to build it shoot me a comment and I will try to get back to you as soon as i can.