src/main/java/Monster/Shade.java

@@ -7,6 +7,7 @@ import static java.util.Objects.*;
 public class Shade extends Monster implements CanMove, CanAttack {
     public static final List<Biomes> HABITAT = Collections.unmodifiableList(Arrays.asList(Biomes.COAST, Biomes.FOREST, Biomes.GRASSLAND, Biomes.MOUNTAIN));
     public static final List<MovementPatterns> MOVES = Collections.unmodifiableList(Arrays.asList(MovementPatterns.ONE_DIAGONAL_STEP));
+    public static final List<Attacks> ATTACKS = Collections.unmodifiableList(Arrays.asList(Attacks.CHILL));
     public static final int MAX_HEALTH = 20;
     public static final int MAX_ENERGY = 14;
 
@@ -68,7 +69,10 @@ public class Shade extends Monster implements CanMove, CanAttack {
         if (attack.cost > energy) {
             return false;
         }
-
+        if (attackIsNotInArsenal(attack)) {
+            return false;
+        }
+        player.setHealth(player.getHealth() - attack.cost);
         return true;
     }
 
@@ -146,4 +150,8 @@ public class Shade extends Monster implements CanMove, CanAttack {
     private boolean noPlayerIsAtPosition(Position position, World world) {
         return !playerIsAtPosition(position, world);
     }
+
+    private boolean attackIsNotInArsenal(Attacks attack) {
+        return !ATTACKS.contains(attack);
+    }
 }

src/main/java/Monster/Troll.java

@@ -12,6 +12,7 @@ import static java.util.Objects.isNull;
 public class Troll extends Monster implements CanMove, CanAttack {
     public static final List<Biomes> HABITAT = Collections.unmodifiableList(Arrays.asList(Biomes.FOREST, Biomes.MOUNTAIN));
     public static final List<MovementPatterns> MOVES = Collections.unmodifiableList(Arrays.asList(MovementPatterns.ONE_DIAGONAL_STEP, MovementPatterns.TWO_STEPS_IN_STRAIGHT_LINE));
+    public static final List<Attacks> ATTACKS = Collections.unmodifiableList(Arrays.asList(Attacks.STOMP));
     public static final int MAX_HEALTH = 80;
     public static final int MAX_ENERGY = 100;
 
@@ -73,7 +74,10 @@ public class Troll extends Monster implements CanMove, CanAttack {
         if (attack.cost > energy) {
             return false;
         }
-
+        if (attackIsNotInArsenal(attack)) {
+            return false;
+        }
+        player.setHealth(player.getHealth() - attack.cost);
         return true;
     }
 
@@ -151,4 +155,8 @@ public class Troll extends Monster implements CanMove, CanAttack {
             energy = MIN_ENERGY;
         }
     }
+
+    private boolean attackIsNotInArsenal(Attacks attack) {
+        return !ATTACKS.contains(attack);
+    }
 }

src/test/java/MonsterTest.java

@@ -173,8 +173,23 @@ public class MonsterTest {
     }
 
     @Test
-    void use_of_attack_not_in_arsenal_is_rejected() {
+    void attack_rejected_when_not_in_arsenal_troll() {
+        assertThat(false, equalTo(defaultTroll.performAttack(Attacks.CHILL, mockPlayer)));
     }
 
+    @Test
+    void attack_rejected_when_not_in_arsenal_shade() {
+        assertThat(false, equalTo(defaultShade.performAttack(Attacks.STOMP, mockPlayer)));
+    }
+
+    @Test
+    void troll_can_attack_player() {
+        assertThat(true, equalTo(defaultTroll.performAttack(Attacks.STOMP, mockPlayer)));
+    }
+
+    @Test
+    void shade_can_attack_player() {
+        assertThat(true, equalTo(defaultShade.performAttack(Attacks.CHILL, mockPlayer)));
+    }
 
 }