diff --git a/.forgejo/workflows/qs.yml b/.forgejo/workflows/qs.yml
index 6d48d25..de9bbf4 100644
--- a/.forgejo/workflows/qs.yml
+++ b/.forgejo/workflows/qs.yml
@@ -28,6 +28,17 @@ jobs:
       - name: "Stop Gradle"
         run: gradle --stop
 
+  async:
+    name: "Validate Async API Specification"
+    runs-on: stable
+    container:
+      image: asyncapi/cli:latest
+    steps:
+      - name: "Checkout"
+        uses: "https://git.euph.dev/actions/checkout@v3"
+      - name: run
+        run: asyncapi validate ws/ws.yml
+
   linting:
     name: "Linting"
     runs-on: stable
diff --git a/build.gradle.kts b/build.gradle.kts
index ca54b5c..6e67ef7 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -61,6 +61,9 @@ dependencies {
     // Postgres
     runtimeOnly("org.postgresql:postgresql")
 
+    // JOML
+    implementation("org.joml:joml:1.10.7")
+
     // Lombok
     compileOnly("org.projectlombok:lombok")
     annotationProcessor("org.projectlombok:lombok")
diff --git a/src/main/java/de/towerdefence/server/game/Enemy.java b/src/main/java/de/towerdefence/server/game/Enemy.java
index 3a7828f..dc21088 100644
--- a/src/main/java/de/towerdefence/server/game/Enemy.java
+++ b/src/main/java/de/towerdefence/server/game/Enemy.java
@@ -2,12 +2,11 @@ package de.towerdefence.server.game;
 
 import lombok.AllArgsConstructor;
 import lombok.Getter;
-import lombok.Setter;
 
 @Getter
-@Setter
 @AllArgsConstructor
 public class Enemy {
-    private int poxX;
-    private int posY;
+    protected int id;
+    protected int x;
+    protected int y;
 }
diff --git a/src/main/java/de/towerdefence/server/game/GameSession.java b/src/main/java/de/towerdefence/server/game/GameSession.java
index 5e04282..fcaee35 100644
--- a/src/main/java/de/towerdefence/server/game/GameSession.java
+++ b/src/main/java/de/towerdefence/server/game/GameSession.java
@@ -1,18 +1,27 @@
 package de.towerdefence.server.game;
 
+import java.lang.reflect.Constructor;
+import java.time.Instant;
+import java.util.ArrayList;
+import java.util.List;
+
+import de.towerdefence.server.game.callbacks.EnemiesChangedCallback;
 import de.towerdefence.server.game.callbacks.PlayerMoneyCallback;
+import de.towerdefence.server.game.callbacks.PlayerHitpointsCallback;
 import de.towerdefence.server.game.exeptions.InvalidPlacementException;
 import de.towerdefence.server.game.exeptions.InvalidPlacementReason;
+import de.towerdefence.server.game.exeptions.WaveInProgressException;
 import de.towerdefence.server.player.Player;
 import lombok.Getter;
+import org.joml.Vector2i;
 
 public class GameSession {
     final static int START_HITPOINTS = 100;
     final static int START_MONEY = 50;
-    final static int MAP_SIZE_X = 10;
-    final static int MAP_SIZE_Y = 20;
-
-    private final Tower[][] towers = new Tower[MAP_SIZE_X][MAP_SIZE_Y];
+    final static Vector2i MAP_SIZE = new Vector2i(10, 20);
+    final static int WAVE_SPAWN_DELAY = 200; // ms
+    final static Vector2i WAVE_SPAWN = new Vector2i(5, 0);
+    final static Vector2i WAVE_TARGET = new Vector2i(5, 19);
 
     private final Player player;
     @Getter
@@ -20,19 +29,77 @@ public class GameSession {
     @Getter
     private int playerHitpoints;
     private final PlayerMoneyCallback moneyCallback;
-    //private final PlayerHitpointsCallback hitpointsCallback;
+    private final PlayerHitpointsCallback hitpointsCallback;
+    private final EnemiesChangedCallback enemyCallback;
 
-    public GameSession(Player player, PlayerMoneyCallback moneyCallback) {
+    private final Tower[][] towers = new Tower[MAP_SIZE.x][MAP_SIZE.y];
+    private final Enemy[][] enemies = new Enemy[MAP_SIZE.x][MAP_SIZE.y];
+    private List<Enemy> wave = new ArrayList<>();
+    private long lastSpawn = Instant.now().toEpochMilli();
+
+    public GameSession(
+            Player player,
+            PlayerMoneyCallback moneyCallback,
+            PlayerHitpointsCallback hitpointsCallback,
+            EnemiesChangedCallback enemyCallback) {
         this.player = player;
         this.moneyCallback = moneyCallback;
-        //this.hitpointsCallback = hitpointsCallback;
+        this.hitpointsCallback = hitpointsCallback;
+        this.enemyCallback = enemyCallback;
         this.money = START_MONEY;
         this.playerHitpoints = START_HITPOINTS;
 
     }
 
+    public void startWave(List<Enemy> enemies) throws WaveInProgressException {
+        if (wave.size() > 0) {
+            throw new WaveInProgressException();
+        }
+        wave = enemies;
+    }
+
+    public void update() {
+        List<Enemy> newEnemies = new ArrayList<>();
+
+        List<Enemy> changedEnemies = moveEnemies();
+
+        if (wave.size() > 0 && shouldSpawn()) {
+            enemies[WAVE_SPAWN.x][WAVE_SPAWN.y] = wave.removeFirst();
+            newEnemies.add(enemies[WAVE_SPAWN.x][WAVE_SPAWN.y]);
+        }
+
+        if (newEnemies.size() > 0 || changedEnemies.size() > 0) {
+            enemyCallback.call(
+                    player,
+                    newEnemies.toArray(new Enemy[newEnemies.size()]),
+                    changedEnemies.toArray(new Enemy[changedEnemies.size()]));
+        }
+    }
+
+    private boolean shouldSpawn() {
+        return lastSpawn + WAVE_SPAWN_DELAY < Instant.now().toEpochMilli()
+                && enemies[WAVE_SPAWN.x][WAVE_SPAWN.y] == null;
+    }
+
+    private List<Enemy> moveEnemies() {
+        // List<Enemy> changedEnemies = moveEnemies();
+
+        // TODO: Implement Moving of Enemies (possibly through A*)
+        throw new RuntimeException("NOT IMPLEMENTED");
+
+        // return changedEnemies;
+
+    }
+
+    /**
+     * @return the next position to go to
+     */
+    private Vector2i pathfinding(Vector2i start, Vector2i target) {
+
+    }
+
     public void placeTower(Tower tower, int x, int y) throws InvalidPlacementException {
-        if (x < 0 || y < 0 || x + 1 > MAP_SIZE_X || y + 1 > MAP_SIZE_Y) {
+        if (x < 0 || y < 0 || x + 1 > MAP_SIZE.x || y + 1 > MAP_SIZE.y) {
             throw new InvalidPlacementException(InvalidPlacementReason.OUT_OF_BOUNDS);
         }
         if (towers[x][y] != null) {
@@ -41,8 +108,13 @@ public class GameSession {
         if (money < Tower.COST) {
             throw new InvalidPlacementException(InvalidPlacementReason.NOT_ENOUGH_MONEY);
         }
+
+        // TODO: Do Pathfinding check for the placement
+
         money -= Tower.COST;
         moneyCallback.call(player, money);
+        tower.x = x;
+        tower.y = y;
         towers[x][y] = tower;
     }
 
diff --git a/src/main/java/de/towerdefence/server/game/Tower.java b/src/main/java/de/towerdefence/server/game/Tower.java
index 48a0c3d..a4a9f64 100644
--- a/src/main/java/de/towerdefence/server/game/Tower.java
+++ b/src/main/java/de/towerdefence/server/game/Tower.java
@@ -1,5 +1,13 @@
 package de.towerdefence.server.game;
 
+import lombok.Getter;
+
+@Getter
 public class Tower {
     public static final int COST = 20;
+    protected int x;
+    protected int y;
+
+    public Tower() {
+    }
 }
diff --git a/src/main/java/de/towerdefence/server/game/callbacks/EnemiesChangedCallback.java b/src/main/java/de/towerdefence/server/game/callbacks/EnemiesChangedCallback.java
new file mode 100644
index 0000000..06f4a49
--- /dev/null
+++ b/src/main/java/de/towerdefence/server/game/callbacks/EnemiesChangedCallback.java
@@ -0,0 +1,9 @@
+package de.towerdefence.server.game.callbacks;
+
+import de.towerdefence.server.game.Enemy;
+import de.towerdefence.server.player.Player;
+
+@FunctionalInterface
+public interface EnemiesChangedCallback {
+    void call(Player player, Enemy[] newEnemies, Enemy[] changedEnemies);
+}
diff --git a/src/main/java/de/towerdefence/server/game/callbacks/PlayerHitpointsCallback.java b/src/main/java/de/towerdefence/server/game/callbacks/PlayerHitpointsCallback.java
index ed1e959..83badd3 100644
--- a/src/main/java/de/towerdefence/server/game/callbacks/PlayerHitpointsCallback.java
+++ b/src/main/java/de/towerdefence/server/game/callbacks/PlayerHitpointsCallback.java
@@ -1,4 +1,4 @@
-package de.towerdefence.server.match.callbacks;
+package de.towerdefence.server.game.callbacks;
 
 import de.towerdefence.server.player.Player;
 
diff --git a/src/main/java/de/towerdefence/server/game/exeptions/WaveInProgressException.java b/src/main/java/de/towerdefence/server/game/exeptions/WaveInProgressException.java
new file mode 100644
index 0000000..90c8518
--- /dev/null
+++ b/src/main/java/de/towerdefence/server/game/exeptions/WaveInProgressException.java
@@ -0,0 +1,4 @@
+package de.towerdefence.server.game.exeptions;
+
+public class WaveInProgressException extends RuntimeException {
+}
diff --git a/src/main/java/de/towerdefence/server/game/pathfinding/AStar.java b/src/main/java/de/towerdefence/server/game/pathfinding/AStar.java
new file mode 100644
index 0000000..d4a4f00
--- /dev/null
+++ b/src/main/java/de/towerdefence/server/game/pathfinding/AStar.java
@@ -0,0 +1,5 @@
+package de.towerdefence.server.game.pathfinding;
+
+public class AStar {
+
+}
diff --git a/src/main/java/de/towerdefence/server/game/pathfinding/NoPathException.java b/src/main/java/de/towerdefence/server/game/pathfinding/NoPathException.java
new file mode 100644
index 0000000..ce36e57
--- /dev/null
+++ b/src/main/java/de/towerdefence/server/game/pathfinding/NoPathException.java
@@ -0,0 +1,4 @@
+package de.towerdefence.server.game.pathfinding;
+
+public class NoPathException extends RuntimeException {
+}
diff --git a/src/main/java/de/towerdefence/server/match/Match.java b/src/main/java/de/towerdefence/server/match/Match.java
index dad8e97..b9cd016 100644
--- a/src/main/java/de/towerdefence/server/match/Match.java
+++ b/src/main/java/de/towerdefence/server/match/Match.java
@@ -1,7 +1,12 @@
 package de.towerdefence.server.match;
 
-import de.towerdefence.server.match.callbacks.PlayerHitpointsCallback;
-import de.towerdefence.server.match.callbacks.PlayerMoneyCallback;
+import de.towerdefence.server.game.callbacks.PlayerHitpointsCallback;
+import java.util.Optional;
+
+import de.towerdefence.server.game.GameSession;
+import de.towerdefence.server.game.callbacks.EnemiesChangedCallback;
+import de.towerdefence.server.game.callbacks.PlayerMoneyCallback;
+import de.towerdefence.server.game.callbacks.PlayerHitpointsCallback;
 import de.towerdefence.server.player.Player;
 import lombok.Getter;
 
@@ -47,21 +52,21 @@ public class Match {
     }
 
     public void connectPlayer(
-        Player player,
-        PlayerMoneyCallback moneyCallback,
-        PlayerHitpointsCallback hitpointsCallback
-    ) {
+            Player player,
+            PlayerMoneyCallback moneyCallback,
+            PlayerHitpointsCallback hitpointsCallback,
+            EnemiesChangedCallback enemyCallback) {
         boolean isPlayer1 = player1.equals(player);
         boolean isPlayer2 = player2.equals(player);
         if (!isPlayer1 && !isPlayer2) {
             return;
         }
         if (isPlayer1 && player1Session == null) {
-            this.player1Session = new GameSession(player, moneyCallback);
+            this.player1Session = new GameSession(player, moneyCallback, hitpointsCallback, enemyCallback);
             return;
         }
         if (isPlayer2 && player2Session == null) {
-            this.player2Session = new GameSession(player, moneyCallback);
+            this.player2Session = new GameSession(player, moneyCallback, hitpointsCallback, enemyCallback);
             return;
         }
     }
diff --git a/src/main/java/de/towerdefence/server/match/MatchService.java b/src/main/java/de/towerdefence/server/match/MatchService.java
index 31792e4..63729e7 100644
--- a/src/main/java/de/towerdefence/server/match/MatchService.java
+++ b/src/main/java/de/towerdefence/server/match/MatchService.java
@@ -1,10 +1,9 @@
 package de.towerdefence.server.match;
 
-import de.towerdefence.server.match.callbacks.PlayerHitpointsCallback;
-import de.towerdefence.server.match.callbacks.PlayerMoneyCallback;
-import de.towerdefence.server.match.exeptions.InvalidPlacementException;
-import de.towerdefence.server.match.exeptions.InvalidPlacementReason;
-import de.towerdefence.server.match.exeptions.NotInMatchException;
+import de.towerdefence.server.game.callbacks.PlayerHitpointsCallback;
+import de.towerdefence.server.game.callbacks.PlayerMoneyCallback;
+import de.towerdefence.server.game.exeptions.InvalidPlacementException;
+import de.towerdefence.server.game.exeptions.InvalidPlacementReason;
 import de.towerdefence.server.player.Player;
 import org.springframework.stereotype.Service;
 
@@ -16,14 +15,9 @@ import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 
-import org.springframework.stereotype.Service;
-
 import de.towerdefence.server.game.GameSession;
 import de.towerdefence.server.game.Tower;
-import de.towerdefence.server.game.callbacks.PlayerMoneyCallback;
-import de.towerdefence.server.game.exeptions.InvalidPlacementException;
-import de.towerdefence.server.game.exeptions.InvalidPlacementReason;
-import de.towerdefence.server.player.Player;
+import de.towerdefence.server.game.callbacks.EnemiesChangedCallback;
 
 @Service
 public class MatchService {
@@ -62,19 +56,19 @@ public class MatchService {
     }
 
     public void playerConnected(
-        Player player,
-        PlayerMoneyCallback moneyCallback,
-        PlayerHitpointsCallback hitpointsCallback
-    ) {
+            Player player,
+            PlayerMoneyCallback moneyCallback,
+            PlayerHitpointsCallback hitpointsCallback,
+            EnemiesChangedCallback enemyCallback) {
         Match match = playerMatches.get(player);
-        match.connectPlayer(player, moneyCallback, hitpointsCallback);
+        match.connectPlayer(player, moneyCallback, hitpointsCallback, enemyCallback);
         Optional<GameSession> optionalPlayerSession = match.getPlayerGameSession(player);
         if (optionalPlayerSession.isEmpty()) {
             return;
         }
         GameSession playerSession = optionalPlayerSession.get();
         moneyCallback.call(player, playerSession.getMoney());
-        hitpointsCallback.call(player, playerSession.getPlayerHitpoints() );
+        hitpointsCallback.call(player, playerSession.getPlayerHitpoints());
         if (!match.hasMatchStarted()) {
             return;
         }
diff --git a/src/main/java/de/towerdefence/server/server/channels/match/MatchWebsocketHandler.java b/src/main/java/de/towerdefence/server/server/channels/match/MatchWebsocketHandler.java
index fa69142..866b332 100644
--- a/src/main/java/de/towerdefence/server/server/channels/match/MatchWebsocketHandler.java
+++ b/src/main/java/de/towerdefence/server/server/channels/match/MatchWebsocketHandler.java
@@ -11,6 +11,7 @@ import org.springframework.web.socket.WebSocketSession;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 
+import de.towerdefence.server.game.Enemy;
 import de.towerdefence.server.game.exeptions.InvalidPlacementException;
 import de.towerdefence.server.match.MatchService;
 import de.towerdefence.server.match.NotInMatchException;
@@ -41,12 +42,20 @@ public class MatchWebsocketHandler extends JsonWebsocketHandler {
         super.afterConnectionEstablished(session);
         playerSessions.put(sessionPlayers.get(session), session);
         matchService.playerConnected(
-            sessionPlayers.get(session),
-            this::onPlayerMoneyChanged,
-            this::onPlayerHitpointsChanged
+                sessionPlayers.get(session),
+                this::onPlayerMoneyChanged,
+                this::onPlayerHitpointsChanged,
+            	this::onEnemiesChanged
         );
     }
 
+    @Override
+    protected void closeSession(WebSocketSession session, CloseStatus reason) {
+        Player player = sessionPlayers.get(session);
+        super.closeSession(session, reason);
+        playerSessions.remove(player);
+    }
+
     private void onPlayerMoneyChanged(Player player, int playerMoney) {
         WebSocketSession session = playerSessions.get(player);
         try {
@@ -63,11 +72,8 @@ public class MatchWebsocketHandler extends JsonWebsocketHandler {
         }
     }
 
-    @Override
-    protected void closeSession(WebSocketSession session, CloseStatus reason) {
-        Player player = sessionPlayers.get(session);
-        super.closeSession(session, reason);
-        playerSessions.remove(player);
+    private void onEnemiesChanged(Player player, Enemy[] newEnemies, Enemy[] changedEnemies) {
+
     }
 
     @Override
@@ -75,9 +81,8 @@ public class MatchWebsocketHandler extends JsonWebsocketHandler {
         try {
             String payload = message.getPayload();
             if (!Objects.equals(
-                objectMapper.readTree(payload).get("$id").asText(),
-                RequestTowerPlacingMessage.MESSAGE_ID
-            )) {
+                    objectMapper.readTree(payload).get("$id").asText(),
+                    RequestTowerPlacingMessage.MESSAGE_ID)) {
                 this.closeSession(session, CloseStatus.BAD_DATA);
                 return;
             }
@@ -89,16 +94,15 @@ public class MatchWebsocketHandler extends JsonWebsocketHandler {
     }
 
     private void handleRequestTowerPlacingMessage(
-        WebSocketSession session,
-        String payload
-    ) throws IOException {
+            WebSocketSession session,
+            String payload) throws IOException {
         RequestTowerPlacingMessage msg = objectMapper.readValue(payload, RequestTowerPlacingMessage.class);
         Player opponent;
         try {
             opponent = this.matchService.placeTower(
-                this.sessionPlayers.get(session),
-                msg.getX(),
-                msg.getY()
+                    this.sessionPlayers.get(session),
+                    msg.getX(),
+                    msg.getY()
             );
         } catch (InvalidPlacementException exception) {
             new InvalidPlacementMessage(msg.getX(), msg.getY(), exception.getReason()).send(session);
diff --git a/src/main/java/de/towerdefence/server/server/channels/match/enemy/EnemyUpdateMessage.java b/src/main/java/de/towerdefence/server/server/channels/match/enemy/EnemyUpdateMessage.java
new file mode 100644
index 0000000..c83c359
--- /dev/null
+++ b/src/main/java/de/towerdefence/server/server/channels/match/enemy/EnemyUpdateMessage.java
@@ -0,0 +1,61 @@
+package de.towerdefence.server.server.channels.match.enemy;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import com.fasterxml.jackson.databind.node.JsonNodeFactory;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+
+import de.towerdefence.server.game.Enemy;
+import de.towerdefence.server.server.JsonMessage;
+import lombok.AllArgsConstructor;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collector;
+import java.util.stream.Collectors;
+
+@AllArgsConstructor
+public class EnemyUpdateMessage extends JsonMessage {
+
+    private final Enemy[] newEnemies;
+    private final Enemy[] changedEnemies;
+
+    @Override
+    protected String getMessageId() {
+        return "EnemyUpdate";
+    }
+
+    @Override
+    protected Map<String, JsonNode> getData(JsonNodeFactory factory) {
+
+        List<JsonNode> newArray = Arrays
+                .stream(newEnemies)
+                .map((Enemy enemy) -> {
+                    ObjectNode o = factory.objectNode();
+                    o.set("id", factory.numberNode(enemy.getId()));
+                    o.set("x", factory.numberNode(enemy.getX()));
+                    o.set("y", factory.numberNode(enemy.getY()));
+                    return o;
+                })
+                .map(JsonNode.class::cast)
+                .toList();
+
+        List<JsonNode> changedArray = Arrays
+                .stream(changedEnemies)
+                .map((Enemy enemy) -> {
+                    ObjectNode o = factory.objectNode();
+                    o.set("id", factory.numberNode(enemy.getId()));
+                    o.set("x", factory.numberNode(enemy.getX()));
+                    o.set("y", factory.numberNode(enemy.getY()));
+                    return o;
+                })
+                .map(JsonNode.class::cast)
+                .toList();
+
+        return Map.of(
+            "new", new ArrayNode(factory, newArray),
+            "changed", new ArrayNode(factory, changedArray)
+        );
+    }
+}
diff --git a/ws/ws.yml b/ws/ws.yml
index 2ac309b..d512df7 100644
--- a/ws/ws.yml
+++ b/ws/ws.yml
@@ -253,8 +253,23 @@ channels:
           required:
             - $id
             - playerHitpoints
-
-
+      EnemyUpdate:
+        description: All Information needed to updated the Enemy Information in Game
+        payload:
+          type: object
+          additionalProperties: false
+          properties:
+            $id:
+              type: string
+              format: messageId
+            new:
+              type: array
+            changed:
+              type: array
+          required:
+            - $id
+            - new
+            - changed
 
 operations:
   requestConnectionToken:
@@ -343,6 +358,13 @@ operations:
       $ref: "#/channels/match"
     messages:
       - $ref: "#/channels/match/messages/PlayerHitpoints"
+  enemyUpdate:
+    title: EnemyUpdate
+    action: receive
+    channel:
+      $ref: "#/channels/match"
+    messages:
+      - $ref: "#/channels/match/messages/EnemyUpdate"