diff --git a/eco-core/core-plugin/src/main/java/com/willfp/ecobosses/commands/CommandSpawn.java b/eco-core/core-plugin/src/main/java/com/willfp/ecobosses/commands/CommandSpawn.java
index 4bece1f..a24f2b6 100644
--- a/eco-core/core-plugin/src/main/java/com/willfp/ecobosses/commands/CommandSpawn.java
+++ b/eco-core/core-plugin/src/main/java/com/willfp/ecobosses/commands/CommandSpawn.java
@@ -3,7 +3,7 @@ package com.willfp.ecobosses.commands;
 import com.willfp.eco.core.command.CommandHandler;
 import com.willfp.eco.core.command.TabCompleteHandler;
 import com.willfp.eco.core.command.impl.Subcommand;
-import com.willfp.eco.core.config.ConfigUpdater;
+import com.willfp.eco.core.config.updating.ConfigUpdater;
 import com.willfp.ecobosses.EcoBossesPlugin;
 import com.willfp.ecobosses.bosses.EcoBoss;
 import com.willfp.ecobosses.bosses.EcoBosses;
diff --git a/eco-core/core-proxy/src/main/java/com/willfp/ecobosses/proxy/util/CustomEntities.java b/eco-core/core-proxy/src/main/java/com/willfp/ecobosses/proxy/util/CustomEntities.java
new file mode 100644
index 0000000..6470f02
--- /dev/null
+++ b/eco-core/core-proxy/src/main/java/com/willfp/ecobosses/proxy/util/CustomEntities.java
@@ -0,0 +1,30 @@
+package com.willfp.ecobosses.proxy.util;
+
+import com.google.common.collect.BiMap;
+import com.google.common.collect.ImmutableBiMap;
+import com.willfp.ecobosses.proxy.proxies.CustomIllusionerProxy;
+import lombok.experimental.UtilityClass;
+import org.bukkit.entity.LivingEntity;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+@UtilityClass
+public class CustomEntities {
+    /**
+     * Registered custom entities.
+     */
+    private static final BiMap<String, Class<? extends CustomEntity<? extends LivingEntity>>> REGISTRY = new ImmutableBiMap.Builder<String, Class<? extends CustomEntity<? extends LivingEntity>>>()
+            .put("custom_illusioner", CustomIllusionerProxy.class)
+            .build();
+
+    /**
+     * Get entity class.
+     *
+     * @param id The entity id.
+     * @return The class.
+     */
+    @Nullable
+    public Class<? extends CustomEntity<? extends LivingEntity>> getEntityClass(@NotNull final String id) {
+        return REGISTRY.get(id);
+    }
+}
diff --git a/eco-core/core-proxy/src/main/java/com/willfp/ecobosses/proxy/util/CustomEntity.java b/eco-core/core-proxy/src/main/java/com/willfp/ecobosses/proxy/util/CustomEntity.java
new file mode 100644
index 0000000..18709d1
--- /dev/null
+++ b/eco-core/core-proxy/src/main/java/com/willfp/ecobosses/proxy/util/CustomEntity.java
@@ -0,0 +1,7 @@
+package com.willfp.ecobosses.proxy.util;
+
+import org.bukkit.entity.LivingEntity;
+
+public interface CustomEntity<T extends LivingEntity> {
+
+}