[Spell slots and endless spells]

I've searched everywhere and I cant find the answer to this

If I have a wizard who can cast only one spell a turn can they cast that spell and also cast an endless spell? Or does the endless spell take up that casting slot?

[AoS 2 - Nighthaunt Discussion]

On 1/5/2020 at 7:50 AM, shinros said:

So far, (correct me if I'm wrong) this army is more surgical and you have to pick your battles. After all, lore wise it is a vanguard force. So I'm eager for feedback!   

Seems good. Clearly planning on using KoSoES and DG as your hammer, with some Bladegheist and Dreadscythe backup? I'd be worried you might not have enough objective coverage.

[AoS 2 - Nighthaunt Discussion]

1 hour ago, SleeperAgent said:

 

That sucks. But thank you!

[AoS 2 - Nighthaunt Discussion]

Ruler of the Spirit Hosts says "At the start of your hero phase, you can pick a friendly SUMMONABLE NIGHTHAUNT unit within 9" of this general and return D3 slain models to that unit. The returning models must be set up within 9" of this general." Just says "a" and not a number. Does this mean I can select as many units in range as I can?