It is tied to all minor features, such as Wells, Druid Houses. The Minor Feature biome is a biome which also has an area of 1 square meter and is found randomly throughout the forest. This biome is used only for the generation of Major Landmarks in the game code and serves no in-game purpose. Each Major Landmark is tied to a Major Feature biome, which defines the fact that Major Landmarks spawn on a grid pattern with a distance between landmarks on the cardinal axis of 256 meters. The Major Feature biome controls the spawning of Major Landmarks. The Major Feature Biome is a biome which always has an area of 1 square meter and is found at every pair of coordinates where both coordinates are divisible by 256, such as (512, 1024), (2560, 1280) or (0, 0). More lilypads appear on Twilight Streams than vanilla Rivers. No special items, blocks or events spawn or occur here. More often than not, the Twilight Stream serves as a border between two or more biomes and can be seen as such on a Magic Map. The Dark Forest has two exclusive mobs: the Mist Wolf and King Spider that only spawn inside that biome, each of which have specific abilities tailored to the area in which it spawns: the Mist Wolf disappears when under Darkwood Leaves, and the King Spider has twice the size and strength of the Spider. Doing so takes 9 diamonds to get started, but the resulting amount of Wrath Igniters is more than sufficient to level off the whole biome. A Wrath Igniter could be used to clear areas. The leaves are immune to both fire and lava, possibly because of the lag that a fire would cause in such a large biome or more likely because of the intended nature of the biome to be a hostile and frightening realm where strange monsters spawn. It is nearly impossible to get any daylight in a Dark Forest, as Darkwood Leaves take about as long to break as Stone with a Wooden Pickaxe even when using a high-tier pickaxe such as an Advanced Diamond Drill. No lava or water pools can be found below the leaves, as all normal terrain generation features are pushed above the canopy and end up on top of the Darkwood Leaves (except the Hollow Hill, which remains under the canopy). The Dark Forest is occasionally lit by mushroom blocks that provide a minimal amount of light. There is not much room to navigate, as the land is punctuated by tree trunks and there are only 4-5 blocks, at most, of vertical space to move about in. The Dark Forest stays in complete and total darkness, due to the Darkwood Leaves that create a low canopy above the forest floor.

The forest wiki biome