Добавил случайных врагов

Assets/Scripts/EnemySpawner.cs

@@ -8,6 +8,7 @@ public class EnemySpawner : MonoBehaviour
     [SerializeField] private SandPathBuildService _pathBuildService;
     [SerializeField] private Transform _enemyHolder;
     [SerializeField] private Transform _spawnPoint;
+    [SerializeField] private Enemy[] _enemiesPrefabs;
     [SerializeField] private UnityEvent<Enemy> _onEnemySpawned;
 
     public event UnityAction<Enemy> OnEnemySpawned
@@ -43,7 +44,11 @@ public class EnemySpawner : MonoBehaviour
 
         foreach (var prefab in level.EnemiesPrefabs)
         {
-            var enemy = prefab.Spawn(
+            var p = prefab;
+            if (prefab == null)
+                p = _enemiesPrefabs[Random.Range(0, _enemiesPrefabs.Length)];
+
+            var enemy = p.Spawn(
                 level.EnemiesHealthMultiplier,
                 level.EnemiesSpeedMultiplier,
                 level.EnemiesDamagingMultiplier,

Assets/Scripts/ScriptableObjects/Level.cs

@@ -4,6 +4,7 @@ using System.Collections.Generic;
 [CreateAssetMenu(fileName = "Level_No", menuName = "Scriptable Objects/Level")]
 public class Level : ScriptableObject
 {
+    [Tooltip("Если элемент не задан, будет выбран случайный из списка префабов спавнера")]
     [SerializeField] private Enemy[] _enemiesPrefabs;
     [SerializeField] private float _levelTimeSec = 10f;
     [SerializeField] private float _enemiesHealthMultiplier = 1;