A couple of times now, I've seen really awesome Minecrafters get somewhat frustrated trying to figure out how to make a mob Grinder/XP farm. They're players who are awesome at the basics but cant quite figure out how to move to the next level in their survival experience. They're at the mercy of grinding out levels the old fashioned way and dying and losing levels is a huge loss for them. My heart goes out to these guys and gals because I used to be one of them. Grinders seemed too complicated and out of my building league. Every build I saw always required intricate redstone mechanics and piston contraptions and they just seemed like a daunting task to put together and figure out.
One day I got fed up with it and set out to find a really simple, uncomplicated build that didnt require fancy upside down waterfall tunnels or redstone contraptions or pistons. I just wanted a quick easy way to spawn some enemies and get some damn loot.
Then at last I found what I was looking for... A Mob farm that required no redstone, no fancy parts, and was super simple to build.
I've Directed a few players to the same videos and references I used in my search but Its difficult to explain and they don't always get what I wanted them to find, so I decided to compile a bunch of helpful building information to make it easy for inexperienced builders to figure mob farms out.
First up, here is a link to the video that shows the mob farm in question and a quick step by step of the how to. Watch this video first to get an idea of what you need to do:
In this video they use a spider spawner, but this design works for any mob type, and is actually more useful for zombies and skeletons. As an additional note, this is the most basic design for the spawner, there are a couple of quality of life tweaks I'll go over to make the farm even easier to manage.
Next up I'm gonna show you guys my spawners and how to change them just a little bit and make them easier to work with:
To start out all you need to do is dig out a 9x5 block cube around your spawner. Thats 4 blocks in each direction away from the spawner block, and 2 blocks above and below, they go 3 high in the video because he made his in a pre generated dungeon that was that tall already, but mobs don't spawn in that 3rd block layer above the spawner so its unnecessary. Just make sure to put blocks above your spawner so they dont spawn on top of it and get stuck up there.
Next, drop a bucket of water in each corner of the room. This funnels all the mobs down the hole and into your "Kill room". Place the signs as shown in the video. Note: placing them can be kinda tricky, to place a sign on top of another sign you have to hold the shift key while placing it, this also lets you put torches and signs on other interactive items such as furnaces or workbenches if you didn't already know! We place the signs here to stop the water from falling down the shaft. If water went down there, mobs would be able to swim up it and you don't want that happening.
Once you've got the main room finished the rest is fairly simple. You need to dig a 3x3 hole down at least 10 blocks from the base of your spawn room. There is a very important line to draw here... dig too deep and the mobs will die when they hit the floor and you get no xp, also you have to be within 15 blocks of the mob spawner block for it to activate.
This next part depends on exactly what you want from your spawner...
We dig this hole 10 blocks down so that when the mobs fall into it they take fall damage and make the killing process faster, basically they die in one or two hits, awesome, but what about all the goodies they drop? We want that stuff and there are a couple ways of getting it, but that also introduces a couple of problems as well.
The easiest thing to do is to knock out the lowest layer of blocks on the outside perimeter of your shaft, and then place water in the opposite corners of wherever you plan to stand when killing mobs, like so:
This Funnels all the dropped items straight to you after the mobs die. Unfortunately this stops the mobs from taking fall damage, effectively making the whole 10 block deep shaft pointless. So this is where you have to get creative or decisive, if you dont care about the items you can just leave the water out and the xp orbs will float right on over to you no worries, you've got a quick XP farm. but if you want them you just have to deal with slow mob killing or get a little inventive with hoppers.
This video shows a very similar build that uses hoppers instead:
basically you just put hoppers on the ground floor and forget the water, for me even that was too complicated so I just deal with the slightly longer killing time and the water funnel, its more efficient for me. Sharpness 5 sword also makes it a breeze anyway.
BTW, with spider versions of this farm, they will still climb up the walls of the shaft, there's really no way around it, they fall back down once they reach the top and its not really that annoying but its important to mention this as one reason for using the water funnel method, it pushes the spiders towards you and gives them less time to try and climb up the walls. You can also make the shaft shorter, even right under the spawner room if you'd like, because you aren't trying to get fall damage anymore.
Now the last part is setting up your kill room, which might be tricky as the ones shown in both videos are really inefficient and kinda suck... these are what mine look like:
This one is for spiders. The glass blocks are stair stepped so that the water traps them under the 1x3 layer, just another climbing deterrent for them. The gap you see on the floor is there so the spiders don't hit me and poison me through the fence which can happen with cave spider variations, so i just hold shift and move myself to the end of the block until i cant move any further. This puts me out of their range but I can still hit them, then I just fall into the gap to collect items and xp.
Also if it wasn't already obvious, you hit the mobs through the fence post.
This one is for my Zombies. Note: Baby zombies will escape through the fence post, there's no way around this, but its not really a problem, just block off the kill room with a door and stand behind it if you wanna go afk, that's all I do.
Now then, if you're lucky enough to find a zombie spawner like me, you have the added benefit of being able to spawn zombie villagers. If this is the case then I recommend another small tweak to the design.
Dig out around the kill room and put a gate in one side like so. You can see it inside and to the right:
Then make some sort of staging area where you can separate the zombie villager from the extra stragglers that wander out with it, don't forget to close the gate once you get them out of the kill room to stop more from wandering out:
Once I kill off the extra zombies, I break one of the blocks and have the zombie villager chase me down the hallway I keep telling you guys about, originally this was gonna go to my storage room, but as I was making it I kept hearing a lot of groaning above me and I was like why the hell are there so many zombies up there. Lucky me lol.
I just lock them in the hallway while I cure them, I could make this a lot fancier and easier to work with but it gets the job done and I've been busy with more important projects:
Normally the biggest difficulty people have is moving the villagers to wherever they want them, I cant stress this enough, just make them chase you while they're a zombie and take them wherever you want them to end up, then trap them and cure them there. If thats not possible, get them somewhere close and then push them with water buckets the rest of the way.
In my opinion, a zombie spawner should be your ultimate goal. Once you have one, you have an infinite supply of XP to meet all your enchanting needs and a guaranteed way of obtaining villagers to trade with.
Cure enough villagers and eventually you'll have your own market like me! Find the right librarians and you can just buy whatever enchants you need.
That's it folks, remove any and all torches / ladders / building equipment, and close off the spawn room so that absolutely no light gets in and watch em spawn like crazy. With this you should be able to build a very basic mob farm, which honestly I've never felt the need to upgrade. You can add to it all you want though and its a great step off point into more complicated builds that incorporate redstone and pistons and daylight sensors and that you can afk at while it gathers xp for you etc... but that's just not my cup of tea.
Shoutout to @Slattern who motivated me to make an informative post about building these things =P
