CubeSpawnerSystem is an ISystem that runs after CubeSpawner exists on an entity (usually from baking CubeSpawnerAuthoring). It reads Prefab and Amount, computes a cube root side length, triple nested loops walk a 3D index (x,y,z), and each slot gets Instantiate plus LocalTransform at new float3(x,y,z) * 1.5f until spawnedCount reaches Amount. Then it disables itself so you do not spawn every frame.