ZippyMagician

If you want to make a tree, you have to make a class that looks something like this: public class CustomTree extends AbstractTreeFeature<NoFeatureConfig> { public CustomTree() { super(NoFeatureConfig::deserialize); } } You also have to override the place method in this class. The place method places all the blocks you want. Then, go into your features class (or whatever you are using to store different features) and add: public class MyFeatures // If you don't already have a features class make it using something like this name { public static AbstractTreeFeature<NoFeatureConfig> CUSTOM_TREE = new CustomTree(); //... All other features you have } you can then go into your custom biome and add it like this: public class MY_CUSTOM_BIOME extends Biome { public MY_CUSTOM_BIOME { super(Your biome.builder config stuff); // THIS IS WHAT YOU USE this.addFeature( Decoration.VEGETAL_DECORATION, Biome.createDecoratedFeature( MyFeatures.CUSTOM_TREE, IFeatureConfig.NO_FEATURE_CONFIG, Placement.COUNT_EXTRA_HEIGHTMAP, new AtSurfaceWithExtraConfig(0.4F, 10, 1)); } } or, if you want to add it to a biome that already exists (a vanilla biome) for (Biome biome : ForgeRegistries.BIOMES) { biome.addFeature( Decoration.VEGETAL_DECORATION, Biome.createDecoratedFeature( MyFeatures.CUSTOM_TREE, IFeatureConfig.NO_FEATURE_CONFIG, Placement.COUNT_EXTRA_HEIGHTMAP, new AtSurfaceWithExtraConfig(0.4F, 10, 1)) ); } This code would go in your main mod file, under the FMLCommonSetupEvent (you probably called it init or something similar)

Yeah you have to override the End Biome provider, as the default code does not support custom Biomes in the end