This article is from the Skyblock plugin website.
Is the slime ball challenge possible? How would players get slime to spawn on their islands? Even with the swamp biomes players are having no luck.
Build down and make a platform that is lower than level 40. Slimes spawn every 10th chunk on average (chunk = 16×16 blocks) so make the platform as big as possible so that it covers at least 10 chunks. Cover it in torches so other mobs don’t spawn. You may be lucky and find a slime spawning chunk immediately.
Our staff team will not provide you the seed. Instead, you may have to look for a player that may have some or change island biome.