diff --git a/server/creatures/creature_data.cpp b/server/creatures/creature_data.cpp
index 8f86fdb..58fc81a 100644
--- a/server/creatures/creature_data.cpp
+++ b/server/creatures/creature_data.cpp
@@ -21,6 +21,9 @@
 */
 #include "creature_data.hpp"
 
+#include <sstream>
+#include <stdexcept>
+
 CreatureData::CreatureData(std::string _avatar, int _scriptRef):
 	Entity("creature"),
 	avatar(_avatar),
@@ -29,9 +32,29 @@ CreatureData::CreatureData(std::string _avatar, int _scriptRef):
 	//EMPTY
 }
 
-void CreatureData::Update() {
-	Entity::Update();
-	//TODO: (0) call the script reference
+int CreatureData::Update(lua_State* L) {
+	int ret = 0;
+
+	if (scriptRef != 0) {
+		//Call the script reference
+		lua_pushinteger(L, scriptRef);
+		lua_gettable(L, LUA_REGISTRYINDEX);
+		lua_pushlightuserdata(L, reinterpret_cast<void*>(this));
+
+		//check for errors
+		if(lua_pcall(L, 1, 1, 0) != LUA_OK) {
+			std::ostringstream msg;
+			msg << "Error running creature script: " << lua_tostring(L, -1);
+			lua_pop(L, 1);
+			throw(std::runtime_error(msg.str()));
+		}
+
+		ret += lua_tonumber(L, -1);
+	}
+
+	ret += Entity::Update();
+
+	return ret;
 }
 
 //-------------------------
diff --git a/server/creatures/creature_data.hpp b/server/creatures/creature_data.hpp
index 5f841a9..cf4efae 100644
--- a/server/creatures/creature_data.hpp
+++ b/server/creatures/creature_data.hpp
@@ -39,7 +39,7 @@ public:
 	CreatureData(std::string avatar, int scriptRef);
 	~CreatureData() = default;
 
-	virtual void Update();
+	virtual int Update(lua_State*);
 
 	//accessors & mutators
 
diff --git a/server/creatures/creature_manager.cpp b/server/creatures/creature_manager.cpp
index 4b207e8..78fdb37 100644
--- a/server/creatures/creature_manager.cpp
+++ b/server/creatures/creature_manager.cpp
@@ -29,9 +29,14 @@ CreatureManager::~CreatureManager() {
 	UnloadAll();
 }
 
-void CreatureManager::Update() {
+//arg: a list of creatures to be updated in the clients
+int CreatureManager::Update(std::list<CreatureData*>* creatureList) {
+	int ret;
 	for (auto& it : elementMap) {
-		it.second.Update();
+		ret = it.second.Update(lua);
+		if (ret) {
+			creatureList->push_back(&it.second);
+		}
 	}
 }
 
diff --git a/server/creatures/creature_manager.hpp b/server/creatures/creature_manager.hpp
index 7a3f1eb..39a8d29 100644
--- a/server/creatures/creature_manager.hpp
+++ b/server/creatures/creature_manager.hpp
@@ -27,6 +27,7 @@
 #include "sqlite3.h"
 
 #include <functional>
+#include <list>
 #include <map>
 #include <string>
 
@@ -36,7 +37,7 @@ public:
 	~CreatureManager();
 
 	//common public methods
-	void Update();
+	int Update(std::list<CreatureData*>* creatureList);
 
 	int Create(std::string avatar, int scriptRef);
 	void Unload(int uid);
diff --git a/server/entities/entity.cpp b/server/entities/entity.cpp
index 86ae141..b55d85c 100644
--- a/server/entities/entity.cpp
+++ b/server/entities/entity.cpp
@@ -25,8 +25,10 @@ Entity::Entity(const char* _type): type(_type) {
 	//EMPTY
 }
 
-void Entity::Update() {
+int Entity::Update() {
 	origin += motion;
+
+	return motion != 0;
 }
 
 int Entity::SetRoomIndex(int i) {
diff --git a/server/entities/entity.hpp b/server/entities/entity.hpp
index cdce31e..f5fca84 100644
--- a/server/entities/entity.hpp
+++ b/server/entities/entity.hpp
@@ -29,7 +29,7 @@
 //The base class for all objects in the world
 class Entity {
 public:
-	virtual void Update();
+	virtual int Update();
 
 	//accessors & mutators
 	int SetRoomIndex(int i);
diff --git a/server/rooms/room_data.cpp b/server/rooms/room_data.cpp
index aef217e..f3c1b0b 100644
--- a/server/rooms/room_data.cpp
+++ b/server/rooms/room_data.cpp
@@ -43,20 +43,17 @@ void RoomData::RunFrame() {
 	}
 
 	//update the entities in the room
-	creatureMgr.Update();
 	for (auto& it : characterList) {
 		it->Update();
 	}
-	//TODO: (3) trigger script for monsters
 
-	//build a list of game entities
+	//build a list of characters for use with the triggers
 	std::stack<Entity*> entityStack;
 	for (auto& it : characterList) {
 		entityStack.push(it);
 	}
-	//TODO: (3) push the monster entities
 
-	//compare the triggers to the entities, using their real hitboxes
+	//Compare the triggers to the entities, using their real hitboxes
 	//NOTE: this stack solution should prevent problems when modifying the various lists
 	while(entityStack.size()) {
 		//get the entity & hitbox
@@ -101,6 +98,12 @@ void RoomData::RunFrame() {
 		entityStack.pop();
 	}
 
+	//a list of creatures that need to be updated client-side
+	std::list<CreatureData*> creatureList;
+	creatureMgr.Update(&creatureList);
+
+	//TODO: (0) send the updates
+
 	//TODO: creature/character collisions
 }
 
@@ -138,6 +141,7 @@ TriggerManager* RoomData::GetTriggerMgr() {
 
 lua_State* RoomData::SetLuaState(lua_State* L) {
 	lua = L;
+	creatureMgr.SetLuaState(lua);
 	pager.SetLuaState(lua);
 	triggerMgr.SetLuaState(lua);
 	return lua;