[Rx] Spawn prefabs at pre-defined spawn points. There can be a delay before spawning, then the prefabs can be spawned in batches with a delay between each batch.

ListSpawnerRx.cs

using UnityEngine;
using UniRx;
using System;

/// <summary>
/// Spawn prefabs at pre-defined spawn points.
/// There can be a delay before spawning, then the prefabs can be spawned in batches with a delay between each batch.
/// </summary>
public class ListSpawnerRx : MonoBehaviour {

    public GameObject[] PrefabList;
    public Transform[] SpawnPoints;

    public float SpawnDelay = 0f;
    public float SpawnRepeatRate = 0.5f;
    public int SpawnBatchSize = 3;

    struct SpawnEvent {
        public long EnemyId;
        public GameObject Prefab;
        public Transform SpawnPoint;
    }

    void Start () {
        // A Timer that emits a value after the SpawnDelay, then repeats based on the SpawnRepeatRate
        // |0---1---2--->
        var spawnTimer = Observable.Timer(TimeSpan.FromSeconds(SpawnDelay), TimeSpan.FromSeconds(SpawnRepeatRate));

        // Make the spawn timer emit multiple values so that you can spawn multiple enemies per timer tick
        // |012---345---678--->
        var batchSpawnTimer = spawnTimer
            .SelectMany(timerIndex => Observable.Range((int)timerIndex * SpawnBatchSize, SpawnBatchSize));

        // A stream of all the prefabs to be spawned
        var prefabStream = PrefabList.ToObservable();

        // A stream of spawn points that loops so it has enough to handle all the prefabs
        var spawnPointStream = SpawnPoints.ToObservable()
            .Repeat() // Reuse spawn points if there are more Prefabs than Spawn Points
            .Take(PrefabList.Length); // Repeat will infinitely loop and freeze without the Take to limit it

        // Create a stream of SpawnEvents by zipping together 3 streams: batchSpawnTimer, prefabStream, spawnPointStream
        IObservable<SpawnEvent> spawnEventStream = Observable.Zip( batchSpawnTimer, prefabStream, spawnPointStream,
            ( timerLoopIndex, prefab, spawnPoint ) => new SpawnEvent {
                EnemyId = timerLoopIndex,
                Prefab = prefab,
                SpawnPoint = spawnPoint
            });

        // Listen for any Spawn Events and Instantiate the Prefab
        spawnEventStream
            .Subscribe(e => {
                Debug.Log("Spawning Enemy #" + e.EnemyId);
                var newGO = Instantiate(e.Prefab);
                newGO.transform.position = e.SpawnPoint.position;
            }).AddTo(this);
    }
}