diff --git a/fcore/enemy-patch.sml b/fcore/enemy-patch.sml
new file mode 100644
index 0000000..f66d853
--- /dev/null
+++ b/fcore/enemy-patch.sml
@@ -0,0 +1,32 @@
+structure EnemyPatch =
+struct
+  datatype enemy_patch =
+    W_HEALTH of int
+  | W_X of int
+  | W_Y of int
+  | W_X_AXIS of GameType.x_axis
+  | W_Y_AXIS of GameType.y_axis
+
+  fun mkEnemy (id, health, x, y, xAxis, yAxis) =
+    {id = id, health = health, x = x, y = y, xAxis = xAxis, yAxis = yAxis}
+
+  fun withPatch (enemy, patch) =
+    let
+      val {id, health, x, y, xAxis, yAxis} = enemy
+    in
+      case patch of
+        W_HEALTH health => mkEnemy (id, health, x, y, xAxis, yAxis)
+      | W_X x => mkEnemy (id, health, x, y, xAxis, yAxis)
+      | W_X_AXIS xAxis => mkEnemy (id, health, x, y, xAxis, yAxis)
+      | W_Y y => mkEnemy (id, health, x, y, xAxis, yAxis)
+      | W_Y_AXIS yAxis => mkEnemy (id, health, x, y, xAxis, yAxis)
+    end
+
+  fun withPatches (enemy, lst) =
+    case lst of
+      hd :: tl =>
+        let val enemy = withPatch (enemy, hd)
+        in withPatches (enemy, tl)
+        end
+    | [] => enemy
+end
diff --git a/oms.mlb b/oms.mlb
index 050a991..8f792f3 100644
--- a/oms.mlb
+++ b/oms.mlb
@@ -18,6 +18,7 @@ fcore/enemy.sml
 fcore/game-type.sml
 
 fcore/player-patch.sml
+fcore/enemy-patch.sml
 
 fcore/physics.sml
 fcore/player.sml