This is a painstakingly long process. It requires a lot of patience.

Things you'll need:
Lots and lots of a building block of your preference.
A lot of torches.
Lots of time, and patience.

Because the seed isn't given nor acquirable you need to go about this the hard way.

1. Build a large platform under your skyblock below y:40. I'd recommend using half-slabs because they're much easier to obtain. I made my platform 40x40

2. Light the thing up. Make sure you're prepared and bring a lot of torches.

3. Look for slimes. If you're lucky at least one will spawn if not you'll have to expand. Easiest way to tell if there are slimes is to just leave your game on, at your island spawn, for about 10 minutes, then go back down and check.

4. Chances are they didn't spawn in the middle of the platform. To create the farm accurately you need to see the slime spawn. It won't move for a couple seconds, it's just to determine the block it spawns on. After that you need to measure the chunk which the block is in. Do so by mapping out the (x) and (z) coords and checking if they are divisible by 16.

5. If everything is right, then you should have slimes spawning. Make a fence or wall around the spawn chunk I'd recommend adding a glowstone grid like ceiling 3 or 4 blocks high to make sure the place is well lit.

6. That's it. If you have any problems with this method just post it here.

 

My pedobear is better than yours.

Nice guide btw, I will try this out (when I get the chance).

 

Chances are in Skyblock.net, you're not going to find any, and if you do, very little. Back then before the /warp Mob was created, I had slimes spawning all over the places. My platform was a 101x101 area with a y=18. Now I don't have any slimes and need to manually spawn them

 

Can you write in the main server, making more mob spawning?

 

Pedo bear and this bear r the same I love both

 

i think maybe if they just either took out a few of the spawners at /warp mob cause im sure they have to have at least 30 there because of the rate and quantity of mobs that spawn in the short amount of time. If they reduce the amount of mobs spawning in the /warp mob, yes it might or might not be as fun, but it would at least give the skyblock players the chance for there own mobs spawning on there own island.

 

then, the rich people would make huge spawners and the poor or starters would be here again.
look at the good side: i found 4 gold ingots, a diamond pickaxe, a stack of redstone and slimeball in mob arena.

 

You lucky duck, i wish i was that lucky

 

And I don't even speak about splash potions and normal potions. And the biggest catch: I got a full set of diamond armor with a set of diamond tools today!!!
And I don't even know why does everyone call me Lucky Piggie...