How To Build a Hostile Mob Farm in Minecraft
The game of Minecraft seems simple enough on the surface. During the day you gather resources and build whatever you want, and at night you either hide from or fight the swarms of monsters that come out in the dark. Most players view these monsters as a nuisance at best or a scourge upon the land at worst, but in reality, they are as much a resource to be gathered as is cobblestone and iron and that’s what we’re going to be looking at today, how to go about building a hostile mob farm.
So, the first step in making your own hostile mob farm is digging into the game mechanics and learning what conditions are necessary for hostile mobs to spawn. Of course, everyone is already aware that hostile mobs spawn at night, so darkness is going to be a necessity. Specifically, a light level of 7 or below will be necessary to allow mobs to spawn.
This means we need to control the level of light in the area we want mobs to spawn which we can call our spawning area or spawning platform. There are a couple of ways to do this. First of all, we could build a room and put a roof directly on it. This will block out sunlight and light from any other sources (torches in your base, pools of lava, etc.) that might be near enough to cast light into the hostile mob farm. The second method is similar to the first but requires you to build a wide detached roof that extends at least 8 blocks past where you want mobs to spawn. The roof casts a pillar of shadow straight down blocking out sunlight from your spawning platforms. This is most useful if for some reason you don’t want walls on your mob farm, but you still have to keep strong light sources away from the spawning area.
This also means that if we want any static lighting (aka, lights we can’t turn on and off) we will need to use things that produce a light level no higher than 7 (Redstone torches, two or one candlesticks, mushrooms, etc.). That said, it obviously doesn’t hurt to have total darkness inside the spawning area so feel free to leave it dark.
Next, hostile mobs need a solid, opaque block to spawn on with a block of air directly above it (most hostile mobs require 2 blocks of air to accommodate their height. Enderman requires 3 blocks of air). This means we’ll want to make sure our spawning platform is made of solid blocks (half slabs work as well as long as they’re in the upper position and so are flush with the tops of surrounding normal blocks). We will also want to make sure that nothing is on the blocks that would prevent mobs from spawning (water, Redstone dust, pressure plates, etc.).
Finally, hostile mobs spawn in an area around the player. Obviously, the game designers didn’t want things spawning right next to you so hostile mobs cannot spawn within 24 blocks of where you are standing. They can spawn anywhere within a 144-block radius of where you’re standing, but they attempt to spawn most frequently between 25 and 32 blocks away from the player.
This means we’re going to want a place for our player to stand that puts the spawning area in that sweet spot of 25 to 32 blocks. The reality is, it’s going to be hard to get the whole farm in this area, but that’s ok, as long as none of the spawning area is 24 blocks or closer to where you’ll be standing in order to use the farm.
While technically this is all the information you absolutely need to design a working mob farm, there is one other mechanic to consider; hostile mob cap. You can have up to 70 hostile mobs in an area before the game will not allow any new hostile mobs to spawn. So, if we make our mob farm and meet all the conditions above, mobs will spawn in it until there are 70 and then it will stop. In order to make the farm efficient, we need to move the mobs from wherever they spawn to a place where they can be killed and their drops collected to keep the farm from hitting that cap so it can continue to spawn mobs. This can be a passive killing mechanism or a holding area for the player to interact with (allowing you to get XP and rare drops in addition to normal drops).
Now that we understand the requirements for our farm, let’s look at exactly how to build our farm. There are literally hundreds of designs out there, and I encourage you, now that you know the mechanics behind it to come up with your own designs that fit the needs of your world. However, to give you a starting point, I’ll show you a hostile mob farm that I use frequently in my worlds that is easy to build at the start of the game and is relatively easy to upgrade later with extra features like a lighting system to stop spawning, or a water flushing system to force mobs off the spawning platforms more quickly.
First thing’s first let’s build the killing platform where we will stand to kill the mobs. For this farm, we’ll place a double chest, then place a hopper leading down into the chest with two more hoppers leading into that hopper.
Next, we’ll place three more hoppers leading into the hoppers we already placed.
Now, we’ll do the same thing on the other side to make a 3×3 platform of hoppers. This is where the hostile mobs will stand waiting for the player to kill them.
Next, we’ll want to place carpets on top of all the hoppers to keep mobs from accidentally falling into the hoppers and getting stuck. You don’t really want to use pressure plates for this because they make a ton of noise when mobs walk on them (not mechanically relevant, but it can be annoying to listen to) and when mobs step on them it generates a Redstone signal which will lock the hopper it is on, preventing the hopper from picking up items.
Once you have your carpets down, place some kind of wall or fence all the way around the 3×3 platform of hoppers. You can use whatever material you like or have on hand. I prefer stone materials for this.
Next, you’re going to place a temporary block on one of the segments of wall or fence, then build a ring of solid blocks directly above the wall/fence. Once you have this ring you can remove the temporary block creating a 1 block gap between the top of the fence and the bottom of your freshly placed ring of blocks.
After this, we’re going to build this ring into a tube 21 blocks high. So, build 20 more “rings” on top of the first one.
Next, we’re going to build platforms extending out from the top of the tube. Build one in each direction off of the tube, 5 blocks wide and extending off the tube 8 blocks.
Now build walls on these platforms that are 3 blocks high. When finished this should look like a big plus sign from above.
Now we’re going to build the actual spawning platforms. Level with the top of the walls you just built, fill in the corners of the plus sign with solid blocks so that when you’re done the whole thing looks like a diamond from the top.
Next, we’re going to build a 3-block high wall all the way around this diamond.
Now we need some water. Grab some water buckets and place water at the ends of the plus sign so the water flows down towards the tube at the center.
Next, you’ll need some trap doors. Place these along all the edges of the spawning platforms inside the walls and close them. This will make the mobs think there is a block there to stand on when in fact there’s not, and they will freely wander into the streams of water which will push them into the tube.
Finally, you need to put a roof on the farm to finish it off. Since this farm uses water to move the mobs around it’s not going to be great for enderman so we’ll prevent them from spawning entirely by placing the roof level with the top block of the walls (to allow enderman to spawn, put the roof on top of the walls instead). You’ll also want to make sure to spawn proof the roof by lighting it up, covering it in half slabs, or covering it in water.
Now, just sit at the bottom and wait for the mobs to spawn and fall into your trap. You can kill them however you like. They should be pretty weak from the fall so you can punch them if you like, but eventually, you should get a mending and looting III enchanted sword to get the most use out of the farm.
Not only will killing the mobs yourself grant you experience, but you can also get rare drops like Iron ingots, carrots, and potatoes from zombies, spider’s eyes from spiders, and even weapons and armor from zombies and skeletons. This is all in addition to the normal rotten flesh, bones, arrows, string, and gunpowder you get from normal mobs, and the Redstone dust and Glowstone dust you can get from witches.
Enjoy your new hostile mob farm and all those shiny new resources!