Strongholds

• 128 total, in 8 rings. Ring 1 starts around 1,280-2,816 blocks from spawn.
• Strongholds do not generate under Ocean biomes.

Structures

• Many structures have biome rules: Witch Hut needs Swamp, Igloo needs Snowy, Desert Pyramid needs Desert.
• Village placement is grid-spaced; two villages of the same type rarely sit in adjacent chunks.
• Pillager Outpost cannot be too close to a Village.
• Ocean Monument needs Deep Ocean around it.
• Ancient City, End City, and Nether Fortress require the matching dimension.
• Trial Chamber requires 1.21+ and Trail Ruins requires 1.20+.

Biomes

• Lush Caves, Dripstone Caves, and Deep Dark are underground-only. Search at Underground or Y -51.
• Mushroom Fields is rare; expect longer searches.
• M biome variants are rarer than their base biome.

Speed tip: start with the rarest criterion and radius 2k-4k. If 30s returns 0 hits, the rule is probably too strict.