How to Build a Slime Farm with Oozing Splash Potions in Minecraft 1.21

Minecraft 1.21 brings some new effects and potions into the game and I've been thinking about how to make some mob farms out of these.

First up is a slime farm with the Oozing potion!

If you give a mob the oozing effect, when they die, they have a chance of spawning a slime. We can use this! We can use it on hostile mobs, like skeletons or zombies, which if you can find a spawner and hit them with the oozing effect them, you get slimes in addition to their drops when you kill them. You can also give friendly mobs the oozing effect in a mob farm, and get slimes that way. This is what we're going to do!

Overview

The way this farm works expands on a standard entity cramming mob farm. In Java, if you cram too many mobs in one space, they'll die. This mechanic has been used for a long time to create easy, compact mob farms. All you need to do is feed the mobs so they reproduce, and as the mobs enter the same space, some of them die. This is a great way to make passive mob farms with minimal interaction, to get their drops.

If we give these mobs the oozing effect, by throwing splash potion of oozing at them before we feed them, they'll spawn slimes as they die. We'll contain these mobs and kill them with magma cubes.

Then we run a hopper minecart with an unloader under the whole farm to pick up all the drops.

We'll use the slime to create more oozing potions.

How to craft the Splash Potion of Oozing

A potion of oozing is created by brewing awkward potions with slime blocks. So we need 9 slimes to get started with this in the first place. To make them splash potions, we brew those with gunpowder.

Materials Required

• 40 Slabs of your choice (I'm using polished stone)
• 1 or more stacks of building blocks (I'm using polished stone)
• 16 Magma blocks
• 49 Fences
• 2 Dispensers
• 5 Powered Rails
• 1 Comparator
• 1 Repeater
• 1 Redstone Torch
• 1 Chest
• 1 Lever
• 43 Rails (it's easier if you have 3 extra when laying the track)
• 3 Redstone Blocks
• 2 Buttons
• 1 Hopper Minecart
• 1 Water bucket
• 9 Splash potions of Oozing

The Unloader

The unloader is pretty easy to make. Put a chest with a hopper going into it with a powered rail on top of the hopper. Put a comparator coming out of the hopper into a block with a Redstone torch on the other side. Put a block on top of the torch with a repeater pointing out into another block over the comparator. Leave it on the default ticks.

This will power the rail whenever there's nothing in the hopper. When a minecart pulls up and starts emptying into the hopper, it will be locked there until the hopper is empty.

The Hopper Minecart Collection System

Place rails zig-zagging across a 7x7 area. I placed three powered rails in the center of rows 2, 4, and 6 with Redstone blocks beneath them. You can do more, but this is enough.

At the end, put another powered rail (under the cart in the picture) with a block on the end with a lever. This is how you stop and start the cart.

If you power the end block, the cart should go back and forth. Put some items in the cart to make sure it works.

Slime Containment

Put a 7x7 platform of your building block exactly on top of the rails with a ring of magma blocks as shown in the picture. Then put a two-high fence around the perimeter. If you make the outer ring beneath the fence magma blocks, the farm will be a bit more efficient killing the slimes faster, but I think this looks better. Eventually the small slimes will jump onto the magma blocks in this configuration.

In the middle, place a 3x3 ring of building blocks with a dispenser facing the open center. The orientation of this doesn't matter.

Place the same blocks again, in the opposite direction. So you end up with two dispensers facing each other on the two different levels.

Put a two wide platform of slabs on top of the fences and inside, so it looks like this.

Put a bucket of water in the bottom dispenser.

Fill the top dispenser with Splash Potions of Oozing

Put buttons on the dispenser and the block above the bottom dispenser. The button over the bottom dispenser will put water into the cavity making it easier to feed the mobs as they bounce around in the water.

We're finished. Now build a stairway up to the top of the platform for you to lure cows in with whatever method you choose. Collect and feed cows, pigs, or sheep until they start to die. By default, that's about 20. You can use chickens, too, but they're a bit more annoying to deal with since they can fly and are always laying eggs clogging things up!

Once all your cows are in place, I like to put a fence post on top to keep me from falling in. It's impossible to get out of this without breaking stuff! Don't fall in!

Using your Slime Farm

Using it is easy! When your cows are ready to breed (this takes several minutes for them to cool down, and 20 minutes for babies to grow up, so it's best to wait for your previous batch of babies to grow), press the button to trigger the splash potion and press the other button to turn on the water.

Then feed the cows.

Don't forget to step up close and get their XP!

As they die, you'll get their drops, and slimes will spawn, getting trapped inside the cage below.

They'll die from the magma cubes. All their drops, plus the cows' drops will get picked up by the hopper minecart and deposited into the chest!

Here's what I got from one feeding with a mob grinder full of adult cows. One splash potion of Oozing, which is 9 slime balls, produced 84, plus beef and leather!

Not too bad! If you wait for all the new baby cows to grow up, you can do this three times an hour. I just stop once in a while while I'm playing to feed the mobs and I'm never short of food. And now slime!

Here's a video version of the build!

Future expansion

When I build this in my survival world, I'll probably bury it two blocks deep to keep the machinery hidden and make the top more accessible.

Use the new crafter block to turn the slime balls into slime blocks after sorting out the other mob drops.

It is possible to automate potions, so with the right setup, you can have the potions getting created automatically with your new slimes, and inserted automatically back into your dispenser!

I'm already picturing a 2x2 expansion of this with 4 mob grinders, one for each type of friendly mob.

Have fun!