ailiujiarui/mineai/the-nether

The Nether (1.21.1)

Portals

• A frame is a rectangle of obsidian (crying obsidian does not count) at least 4 wide and 5 tall, at most 23 x 23; the inside is air. The four corners are optional, so the smallest frame takes 10 obsidian (14 with corners).
• It is lit by fire inside the frame: flint and steel or a fire charge used on the frame's inside, or any fire that lands there. A lit portal fills with purple; standing in it for 4 s changes dimension.
• Coordinates: 1 block in the Nether = 8 blocks in the overworld horizontally (x and z divided by 8; y is unchanged). A portal links to the nearest existing portal around the matching position (search radius 128 blocks in the overworld, 16 in the Nether), else it builds a new one there.
• Explosions (ghast fireballs) can put a portal out without breaking the obsidian; it can be lit again.
• Ruined portals (overworld and Nether) are broken frames with obsidian and crying obsidian already in them, plus a chest of gold loot. Obsidian otherwise forms where water flows onto a lava source.

How the Nether differs

• The space is Y 0 to 127 with bedrock floor and ceiling (the roof is at 123-127). A lava sea fills everything below Y 31; most ground is netherrack over it.
• Water cannot exist: a water bucket evaporates. Ice broken here leaves no water.
• Beds explode when used (a strong blast that sets fires). A respawn anchor charged with glowstone sets the respawn point instead.
• Lava flows farther and faster (7 blocks). Netherrack, once lit, burns forever.
• Compasses and clocks spin; maps still work.
• Items dropped into lava are destroyed, except netherite items, which float.

Biomes

Nether fortress

• Dark nether brick corridors and bridges on stilts, often over the lava sea; it spreads over a wide area and many heights.
• Blaze spawners (usually two, in small rooms on the bridges or at stair landings) and wandering blazes; wither skeletons in the corridors.
• Nether wart grows on soul sand in its stairwells (the brewing base ingredient).
• Chests: diamonds, iron, gold, saddles, horse armor, obsidian, flint and steel.
• A blaze rod drops only when a player (or a tamed wolf) killed the blaze; 0-1 per blaze, Looting adds more. One rod grinds into 2 blaze powder.

Bastion remnant

• Huge blackstone and gilded blackstone buildings with gold blocks, guarded by piglins and piglin brutes (always hostile, 50 HP), and hoglins in the stables.
• Four layouts: housing units, hoglin stables, bridge, and the treasure room (a lava-moat room with gold blocks and a magma cube spawner).
• Chests hold gold, ancient debris, netherite scrap, crying obsidian, enchanted gear, and netherite upgrade smithing templates (always one in the treasure chest; 10% in the other chests). Templates are found nowhere else.

Piglins and gold

• Wearing any one piece of gold armor keeps ordinary piglins neutral. Even then they attack anyone who opens or breaks a chest, barrel or shulker box, or mines gold ore, gold blocks or gilded blackstone near them. Brutes ignore gold.
• Bartering: drop or hand a gold ingot to an adult piglin; it studies it for 6 s and throws something back. About 2% of barters give 2-4 ender pearls; others give obsidian, crying obsidian, fire resistance potions, string, quartz, iron nuggets, soul sand, gravel, blackstone and similar.
• Piglins pick up gold items lying on the ground. Piglins taken out of the Nether turn into zombified piglins after 15 s.

Ancient debris and netherite

A full netherite armor set therefore needs 4 ingots (16 debris and 16 gold ingots), 4 templates (1 found and 3 copies, 21 diamonds) and a diamond set to upgrade (24 diamonds).

Other Nether resources

• Glowstone clusters hang from the ceiling (drop glowstone dust; Fortune helps).
• Nether quartz ore (quartz, experience) and nether gold ore (gold nuggets) are everywhere in netherrack.
• Magma cream from magma cubes, ghast tears from ghasts, crimson and warped fungus, shroomlight, soul sand and soul soil (soul torches, soul campfires).
• Striders walk on lava and can be ridden with a saddle, steered by a warped fungus on a stick.