diff --git a/src/main/java/ru/bclib/api/biomes/SurfaceRuleBuilder.java b/src/main/java/ru/bclib/api/biomes/SurfaceRuleBuilder.java
index c46e3704..bde5b093 100644
--- a/src/main/java/ru/bclib/api/biomes/SurfaceRuleBuilder.java
+++ b/src/main/java/ru/bclib/api/biomes/SurfaceRuleBuilder.java
@@ -1,21 +1,122 @@
 package ru.bclib.api.biomes;
 
+import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.world.level.biome.Biome;
+import net.minecraft.world.level.block.state.BlockState;
 import net.minecraft.world.level.levelgen.SurfaceRules;
 import net.minecraft.world.level.levelgen.SurfaceRules.ConditionSource;
+import net.minecraft.world.level.levelgen.SurfaceRules.RuleSource;
+import net.minecraft.world.level.levelgen.placement.CaveSurface;
+import ru.bclib.api.spawning.SpawnRuleBuilder;
+import ru.bclib.api.spawning.SpawnRuleEntry;
 
+import java.util.Collections;
 import java.util.List;
+import java.util.Map;
+import java.util.function.Supplier;
 
 public class SurfaceRuleBuilder {
+	private static final Map<String, SurfaceRuleEntry> RULES_CACHE = Maps.newHashMap();
 	private static final SurfaceRuleBuilder INSTANCE = new SurfaceRuleBuilder();
-	private List<ConditionSource> conditions;
+	private List<SurfaceRuleEntry> rules = Lists.newArrayList();
+	private SurfaceRuleEntry entryInstance;
+	private ResourceKey<Biome> biomeKey;
 	
 	private SurfaceRuleBuilder() {}
 	
 	public static SurfaceRuleBuilder start() {
+		INSTANCE.biomeKey = null;
+		INSTANCE.rules.clear();
 		return INSTANCE;
 	}
 	
-	public static SurfaceRules.RuleSource build() {
-		return null;
+	/**
+	 * Restricts surface to only one biome.
+	 * @param biomeKey {@link ResourceKey} for the {@link Biome}.
+	 * @return same {@link SurfaceRuleBuilder} instance.
+	 */
+	public SurfaceRuleBuilder biome(ResourceKey<Biome> biomeKey) {
+		this.biomeKey = biomeKey;
+		return this;
+	}
+	
+	/**
+	 * Restricts surface to only one biome.
+	 * @param biome {@link Biome}.
+	 * @return same {@link SurfaceRuleBuilder} instance.
+	 */
+	public SurfaceRuleBuilder biome(Biome biome) {
+		return biome(BiomeAPI.getBiomeKey(biome));
+	}
+	
+	/**
+	 * Set biome surface with specified {@link BlockState}. Example - block of grass in the Overworld biomes
+	 * @param state {@link BlockState} for the ground cover.
+	 * @return same {@link SurfaceRuleBuilder} instance.
+	 */
+	public SurfaceRuleBuilder surface(BlockState state) {
+		entryInstance = getFromCache("surface_" + state.toString(), () -> {
+			RuleSource rule = SurfaceRules.state(state);
+			return new SurfaceRuleEntry(1, SurfaceRules.ifTrue(SurfaceRules.ON_FLOOR, rule));
+		});
+		return this;
+	}
+	
+	/**
+	 * Set biome subsurface with specified {@link BlockState}. Example - dirt in the Overworld biomes.
+	 * @param state {@link BlockState} for the subterrain layer.
+	 * @param depth block layer depth.
+	 * @return same {@link SurfaceRuleBuilder} instance.
+	 */
+	public SurfaceRuleBuilder subsurface(BlockState state, int depth) {
+		entryInstance = getFromCache("subsurface_" + depth + "_" + state.toString(), () -> {
+			RuleSource rule = SurfaceRules.state(state);
+			rule = SurfaceRules.ifTrue(SurfaceRules.stoneDepthCheck(depth, false, false, CaveSurface.FLOOR), rule);
+			return new SurfaceRuleEntry(2, SurfaceRules.ifTrue(SurfaceRules.ON_FLOOR, rule));
+		});
+		return this;
+	}
+	
+	/**
+	 * Set biome filler with specified {@link BlockState}. Example - stone in the Overworld biomes.
+	 * @param state {@link BlockState} for filling.
+	 * @return same {@link SurfaceRuleBuilder} instance.
+	 */
+	public SurfaceRuleBuilder filler(BlockState state) {
+		entryInstance = getFromCache("fill_" + state.toString(), () -> {
+			return new SurfaceRuleEntry(3, SurfaceRules.state(state));
+		});
+		return this;
+	}
+	
+	/**
+	 * Finalise rule building process.
+	 * @return {@link SurfaceRules.RuleSource}.
+	 */
+	public SurfaceRules.RuleSource build() {
+		Collections.sort(rules);
+		SurfaceRules.RuleSource[] ruleArray = rules.toArray(new SurfaceRules.RuleSource[rules.size()]);
+		SurfaceRules.RuleSource rule = SurfaceRules.sequence(ruleArray);
+		if (biomeKey != null) {
+			rule = SurfaceRules.ifTrue(SurfaceRules.isBiome(biomeKey), rule);
+		}
+		return rule;
+	}
+	
+	/**
+	 * Internal function, will take entry from cache or create it if necessary.
+	 * @param name {@link String} entry internal name.
+	 * @param supplier {@link Supplier} for {@link SurfaceRuleEntry}.
+	 * @return new or existing {@link SurfaceRuleEntry}.
+	 */
+	private static SurfaceRuleEntry getFromCache(String name, Supplier<SurfaceRuleEntry> supplier) {
+		SurfaceRuleEntry entry = RULES_CACHE.get(name);
+		if (entry == null) {
+			entry = supplier.get();
+			RULES_CACHE.put(name, entry);
+		}
+		return entry;
 	}
 }
diff --git a/src/main/java/ru/bclib/api/biomes/SurfaceRuleEntry.java b/src/main/java/ru/bclib/api/biomes/SurfaceRuleEntry.java
new file mode 100644
index 00000000..348dbbfb
--- /dev/null
+++ b/src/main/java/ru/bclib/api/biomes/SurfaceRuleEntry.java
@@ -0,0 +1,24 @@
+package ru.bclib.api.biomes;
+
+import net.minecraft.world.entity.Mob;
+import net.minecraft.world.level.levelgen.SurfaceRules;
+import org.jetbrains.annotations.NotNull;
+
+public class SurfaceRuleEntry<M extends Mob> implements Comparable<SurfaceRuleEntry> {
+	private final SurfaceRules.RuleSource rule;
+	private final byte priority;
+	
+	public SurfaceRuleEntry(int priority, SurfaceRules.RuleSource rule) {
+		this.priority = (byte) priority;
+		this.rule = rule;
+	}
+	
+	protected SurfaceRules.RuleSource getRule() {
+		return rule;
+	}
+	
+	@Override
+	public int compareTo(@NotNull SurfaceRuleEntry entry) {
+		return Integer.compare(priority, entry.priority);
+	}
+}
diff --git a/src/main/java/ru/bclib/api/spawning/SpawnRuleEntry.java b/src/main/java/ru/bclib/api/spawning/SpawnRuleEntry.java
index 710860c6..08461e44 100644
--- a/src/main/java/ru/bclib/api/spawning/SpawnRuleEntry.java
+++ b/src/main/java/ru/bclib/api/spawning/SpawnRuleEntry.java
@@ -19,7 +19,7 @@ public class SpawnRuleEntry<M extends Mob> implements Comparable<SpawnRuleEntry>
 		this.rule = rule;
 	}
 	
-	boolean canSpawn(EntityType<M> type, LevelAccessor world, MobSpawnType spawnReason, BlockPos pos, Random random) {
+	protected boolean canSpawn(EntityType<M> type, LevelAccessor world, MobSpawnType spawnReason, BlockPos pos, Random random) {
 		return rule.canSpawn(type, world, spawnReason, pos, random);
 	}