Can a warlock with the UA Moon Bow invocation use the created bow to fire magic ammunition?

Question

The Moon Bow eldritch invocation for warlocks (from Unearthed Arcana: Warlock & Wizard) allows you to go around without ever carrying a weapon or ammunition. You can summon your bow as an action, and then nock back the string and create an arrow instantly that you can fire. This is really, really cool.

You can create a longbow using your Pact of the Blade feature. When you draw back its string and fire, it creates an arrow of white wood, which vanishes after 1 minute. You have advantage on attack rolls against lycanthropes with the bow. When you hit a creature with it, you can expend a spell slot to deal an additional 2d8 radiant damage to the target per spell level.

However, would the bow created by this invocation be able to fire magical ammunition? For example, an arrow of dragon slaying? Or a +1 arrow?

Also, assuming you do use magical ammunition, can you expend spell slots for 2d8 damage per spell level on a hit, or can you only use this function with the white wood arrow created by this invocation?

Answer 1

As written, the bow creates its own ammunition "[w]hen you draw back its string and fire." As such, you cannot fire any other arrows you might happen to have on your person: the one the Moon Bow creates would get in the way.

That said, it would not be game breaking to allow the Moon Bow to fire magical arrows. Yes you will do extra damage but you are expending a magic item and a spell slot to do so.

Answer 2

Seems to me that you would simply be firing two arrows if you used a magical arrow. I'm sure it's unintended but the wording on moonbow is significantly different from the wording on the other 3 pact weapons. By wording, it doesn't create a unique weapon like the mace of dispater, instead it just allows you to create a longbow as a pact weapon and give you special features when you fire it. Technically, by RAW, you could convert a magic bow into your moonbow and retain it's special features, this definitely does not work by RAW for the other 3 pact weapons: regardless, it most likely is not RAI.

Since you aren't notching this arrow and it appears after firing a loaded bow(RAW), then there is nothing stopping you from also firing an arrow as normal from the bow as well. Of course this certainly also isn't RAI and would result in ~double damage per shot. Then again, given the sheer idiocy of some of the "Sage" Advice rulings(dissonant whispers being forced movement for example) who knows what an official ruling on it would be.

Common sense ruling at any table I'd play at would allow you to use your magical ammo, 100% compatible with pact features with no double arrow nonsense. The fluff of [the bow creates a magical arrow when you release the string] is probably best ignored when it comes to rolling dice, like most fluff.

Answer 3

Yes.

You may fire any long bow ammunition from the Moon Bow pact weapon:

You can create a longbow using your Pact of the Blade feature. When you draw back its string and fire, it creates an arrow of white wood, which vanishes after 1 minute. You have advantage on attack rolls against lycanthropes with the bow. When you hit a creature with it, you can expend a spell slot to deal an additional 2d8 radiant damage to the target per spell level.

The Moon Bow creates the white arrow only when the bow is fired. The description does not indicate that the white arrow immediately becomes a projectile, only that it is created.

This falls under the Jeremy Crawford tweet ruling about rules only doing they say they do.

Beware of claims that a rule does something mentioned nowhere in that rule or elsewhere in the core books. There aren't secret rules. (source)

The next time you fire the Moon Bow during the encounter, you could choose to fire the white arrow that was created, or another piece of ammunition.

A consequence of this interpretation is that after 1 minute when your white arrows have vanished, and you decide to use your bow, you will have to use one of your own arrows for the first shot (or dry fire) to create one.

An important point of clarification is that the bow itself is capable of causing the radiant damage by expending a spell slot, nothing to do with the white arrow.

You have advantage on attack rolls against lycanthropes with the bow. When you hit a creature with it, you can expend a spell slot to deal an additional 2d8 radiant damage to the target per spell level.

The the word “it” refers to the last grammatical unit, in this case the bow.

This means you could shoot your magic arrow, expend a spell slot and apply the 2d8 radiant damage in addition to the effects of your magic arrow.

Answer 4

Were I the DM and one of my players asked about this, I would rule that the Warlock could fire pre-existing ammunition, but that the ability to burn a spell slot for the radiant damage requires one of the Moon Bow's whitewood arrows.