Can Imbue Arrow be used with spells from items, spell-like abilities or supernatural effects?

Question

One of my players has a high level rogue and is thinking about taking a dip into Bard and then Arcane Archer, to be more useful when fighting things that don't die from Sneak Attacks. She has a ton of Use Magic Device and access to items created by both the wizard and cleric of the party.

Can a spell stored in a wand, scroll, or ring of spell storing be used to Imbue an arrow?

And in more general terms, an Arcane Archer could be of a race that has spell-like abilities (Drow come to mind) or somehow gain spell-like abilities for other exotic reasons.

Can spell-like abilities be used to Imbue an arrow?

And an even weirder case: she could be the recipient of a Shapechange spell, and turn into something with a supernatural effect that behaves like a spell - an Avoral's fear aura, a Beholder's eye rays (nevermind how it operates a bow), etc. This seems like a more solidly 'no' answer, but I thought I'd include it for completeness.

Answer 1

The details of imbue arrow are... ambiguous. It gives you an extra special way to cast a spell, but offers no details on which spells are allowed (beyond that it be an “area” spell, which is presumably one that has an Area entry but even that might be argued). As written, you could argue that you can pick any area spell ever, regardless of whether or not you are actually able to cast it yourself. And that when you cast it this way, it uses no resources, because you’re casting it via your imbue arrow ability, which makes no mention of resources, rather than through, say, a “spells” ability, which does explain how your limited resources work.

Needless to say, that’s pretty unlikely to be what they meant. Unfortunately, that leaves us in a bit of quandary about what they did mean.¹ At a minimum, anyway, I am going to assume that you have to pick some spell you otherwise can cast, and that when you imbue an arrow with it you use up resources as if you had cast it “normally.”

Based on the use of the word “spell,” I am also going to say spell-like and supernatural abilities are out. Despite being “like” spells, spell-like abilities are not spells and things that references spells generally mean spells and not spell-like abilities. See this Q&A for somewhat more discussion on this. And supernatural abilities are even more removed.

A spell-storing weapon is also probably out—you can only access the spell in a spell-storing weapon by attacking with the weapon, and since it is giving you a special way to cast that spell while imbue arrow wants you to use its special way of casting the spell, they wouldn’t be compatible.

That leaves wands, scrolls, or a ring of spell storing. And happily, all three of these allow you to “cast” spells:

A minor ring of spell storing contains up to three levels of spells that the wearer can cast.

^{(Ring, Spell Storing, Minor)}

If she meets all three requirements but her own caster level is lower than the scroll spell’s caster level, then she has to make a caster level check (DC = scroll’s caster level + 1) to cast the spell successfully. [...]

A spell successfully activated from a scroll works exactly like a spell prepared and cast the normal way.

^{(Scrolls, Activate the Spell and Determine Effect)}

Wands use the spell trigger activation method, so casting a spell from a wand is usually a standard action that doesn’t provoke attacks of opportunity.

^{(Wand, Activation—note that Staff, Activation says the same thing about staves)}

There is still room to argue that these don’t work, however: each of these requires that the user activate the item in order to cast the spell, and imbue arrow doesn’t say anything about activating anything as part of its special casting ability. And again, since imbue arrow doesn’t really explain itself very well, we’re already kind of making up its requirements here.

So ultimately, while we can parse the rules here, we cannot eliminate the ambiguity. You’re better off just making a ruling yourself, as DM. It certainly sounds like you’re OK with this. I would be too—arcane archer is a very weak class, and imbue arrow is about the only thing going for it. And since this rogue likely will not have the ability to use antimagic field—the only thing you can imbue an arrow with and make arcane archer actually worth it—I see little danger in allowing it. And for that matter, I’d allow spell-like and supernatural abilities too—that’s much less ambiguous, but I still see no reason to deny it. And using magic items is a better usage of arcane archer than most I’ve seen.

1. _{It’s worth noting that there are other abilities that similarly involve casting a spell with a weapon. They are generally written more tightly, preventing these ambiguities. This Q&A discusses through several of them, for example—including a spell-storing weapon.}

Answer 2

Yes, with scrolls, wands and the ring of spell storing; not with spell-like or supernatural abilities

As per the SRD:

At 2nd level, an arcane archer gains the ability to place an area spell upon an arrow. When the arrow is fired, the spell’s area is centered on where the arrow lands, even if the spell could normally be centered only on the caster. This ability allows the archer to use the bow’s range rather than the spell’s range. It takes a standard action to cast the spell and fire the arrow. The arrow must be fired in the round the spell is cast, or the spell is wasted.

1. Can a spell stored in a wand, scroll, or ring of spell storing be used to Imbue an arrow?

You have to cast the spell. If using an item counts as casting a spell, you can do it. Otherwise, you cannot. In all your examples, the rules for those specific things suggest that yes, you can. You can with scrolls:

Using a scroll is basically like casting a spell. ... A spell successfully activated from a scroll works exactly like a spell prepared and cast the normal way.

Wands also appear to work:

Wands use the spell trigger activation method, so casting a spell from a wand is usually a standard action that doesn’t provoke attacks of opportunity. (If the spell being cast, however, has a longer casting time than 1 standard action, it takes that long to cast the spell from a wand.)

A ring of spell storing also works:

A minor ring of spell storing contains up to three levels of spells that the wearer can cast.

Nothing in these item descriptions or the imbue ability says you can only use it to cast wizard spells, or only spells you know, or the like. There's some room for DM interpretation, but the most straightforward reading suggests that wands, scrolls and the ring of spell storing all allow you to cast a spell. There's also a certain argument over whether you can actually hold a wand when you're using both hands to fire the arrow, but that's really for the DM to cover (you might cast the spell from the wand before you fire, for example).

2. Can spell-like abilities be used to Imbue an arrow?

No. A spell-like ability is not a spell. Your DM could allow it (say, a drow firing a darkness arrow), but rules-as-written it's not.

3. A supernatural effect that behaves like a spell

No. It's not a spell.