Java Edition 21w40a

21w40a is the fourth snapshot for Java Edition 1.18, released on October 7, 2021, that merges and renames some biomes, tweaks world generation, mob spawning, and fixes bugs.

Blocks

 * Copper Ore
 * Now drop 2-5 Raw Copper when mining instead of 2-3.


 * Stonecutter
 * Block of Copper can be converted to 4 Cut Copper using stonecutter.

Mobs

 * Axolotls
 * Now only spawn in water above clay blocks in lush caves.


 * Cod, Salmon, Pufferfish, Tropical Fish, Squid, and Dolphins
 * Now only spawn in water from Y=50 to Y=64.
 * Additionally, tropical fishes now also spawn in lush caves at any height.


 * Glow Squids
 * Now only spawn in water blocks under Y=30.


 * Goats
 * No longer spawn in Stony Peaks.


 * Zombies
 * Now also spawn in Dripstone Caves again.

World generation

 * Biomes
 * The unused height variation sub-biomes have been removed from the code and merged with their default biome variants, as following:
 * {| class="wikitable collapsible collapsed"

! Removed biomes
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
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 * Some biomes have been renamed:
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 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
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 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"

! Old name !! New name
 * || Windswept Hills
 * || Old Growth Spruce Taiga
 * || Old Growth Pine Taiga
 * || Windswept Gravelly Hills
 * || Sparse Jungle
 * || Jagged Peaks
 * || Windswept Savanna
 * || Frozen Peaks
 * || Snowy Plains
 * || Stony Shore
 * || Old Growth Birch Forest
 * || Wooded Badlands
 * || Windswept Forest
 * }
 * Non-cave biomes (e.g. Savannas) no longer change with height.
 * Tweaked the relative size of some biomes, to match 1.17 a bit closer.
 * Increased the average size of most biomes.
 * || Snowy Plains
 * || Stony Shore
 * || Old Growth Birch Forest
 * || Wooded Badlands
 * || Windswept Forest
 * }
 * Non-cave biomes (e.g. Savannas) no longer change with height.
 * Tweaked the relative size of some biomes, to match 1.17 a bit closer.
 * Increased the average size of most biomes.
 * }
 * Non-cave biomes (e.g. Savannas) no longer change with height.
 * Tweaked the relative size of some biomes, to match 1.17 a bit closer.
 * Increased the average size of most biomes.


 * Ore distribution
 * Copper Ore now generates between Y=-16 and Y=112, generating the most at Y=48, and increased the number of ore blobs.
 * Added more unexposed Diamonds.
 * Decreased minimum generation height of Emerald Ore from Y=32 to Y=-16, and increased the number of blobs.
 * This allows deepslate emerald ore to generate again.
 * Extra gold generates below Y=-48.
 * Decreased minimum generation height of the upper range of Iron Ore from Y=112 to Y=80, and increased the number of blobs.


 * Monster Rooms
 * Increased the amount of monster rooms, especially below Y=0.


 * Gravel
 * Now generates below Y=0, and increased the number of blobs.


 * Lakes
 * Water lakes were removed, because Aquifers could provide local water levels.


 * Magma Blocks
 * Slightly increased the frequency of underwater magma.


 * Villages
 * Now slightly more spread out.


 * General
 * Bedrock layers generate dependent on the world seed now.

Gameplay

 * Advancements
 * Due to the removal or merging of sub-biomes, the number of biomes required to visit for the "Adventuring Time" advancement has been reduced from 42 to 31, with the following biomes now being required:
 * {| class="wikitable collapsed collapsible"

! Required biomes
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General

 * AI
 * Optimized AI for Axolotls, Goats, Hoglins, Zoglins, Piglins, Piglin Brutes and Villagers.

Video
Videos made by slicedlime: