How would crafting a Spell Scroll of Guiding Bolt work for a multiclassed (2019) UA Archivist artificer / Forge cleric?

Question

I'm playing an Archivist Artificer (8) / Forge Cleric (2) in a short campaign. I was trying to figure out how or whether it is possible to create a spell scroll of guiding bolt (or any other spell from either class list).

Xanathar's Guide to Everything (pg. 133) says under the "Scribing a Spell Scroll" downtime activity option:

Scribing a spell scroll takes an amount of time and money related to the level of the spell the character wants to scribe, as shown in the Spell Scroll Costs table. In addition, the character must have proficiency in the Arcana skill and must provide any material components required for the casting of the spell. Moreover, the character must have the spell prepared, or it must be among the character's known spells, in order to scribe a scroll of that spell.

If the scribed spell is a cantrip, the version on the scroll works as if the caster were 1st level.

The May 2019 UA Artificer's Archivist subclass gets the Tools of the Trade feature at 3rd level when they choose the subclass, which grants them the following benets:

Proficiencies. You gain proficiency with calligrapher’s supplies and the forgery kit, assuming you don’t already have them. [...]

Crafting. If you craft a magic item in the scroll category, it takes you a quarter of the normal time, and it costs you half as much of the usual gold.

From this, I have two questions:

• Which attack bonus would the scroll have? Would I use my Intelligence modifier, my Wisdom modifier, or nothing at all?
• How long does the scroll take to craft? Is "one day" of work treated as 8 hours of actual labor by by the character? If so, with the Artificer's 4x work speed and 1/2 cost, would that mean the total amount of time and money spent by the Artificer is 2 hours and 13 gp, for a 25 gp 1st-level scroll?

Answer 1

Spells cast from scrolls use specific fixed DCs/attack bonuses

The effects of Spell Scrolls don't depend on the creator's (or user's) statistics; they have set save DCs and spell attack bonuses based on the level of the spell, as tabulated in the general description of magic scrolls. For Guiding Bolt, that's a first level spell which gives it a +5 attack bonus.

This is part of the balancing factor of having readily available spell scrolls to cast spells with; using scrolls lets you cast many more spells than you might normally be able to, but those spells are probably less powerful/effective than they would be if you were casting them with your own spell slots and getting to use your own modifiers.

It's a bit ambiguous how long it takes the artificer to craft these scrolls

Xanathar's downtime rules require that a character spends at least eight hours working in a given day in order for that day to count as contributing to a downtime activity:

A character must spend at least 8 hours of each day engaged in the downtime activity for that day to count toward the activity's completion.

But most downtime activities have durations measured in weeks, rather than days, so dividing them is a simpler matter. It only gets fiddly with the unusually short time requirements for scribing low-level scrolls and potions of healing.

By a strict RAW interpretation, crafting one scroll is one downtime activity and the character must spend eight hours of the day working on that one activity for the day to count at all, so the Archivist still needs a full working day to make the one scroll. The ability would still be useful for scribing second level and higher scrolls, and it does at least reduce the cost if not the effective crafting time of lesser scrolls.

However, treating a crafting time of "one day" as meaning "eight hours" and letting the artificer work in hours rather than days is a reasonable ruling to make in this circumstance, and so that would allow the Archivist Artificer to scribe cantrip and first level spell scrolls in a couple of hours. Remember that the Artificer is still UA material and this ability might be clarified more specifically in future.

Answer 2

Attack and DCs

The Attack and Spell DC are set for scrolls, not based on the crafter or caster.

The level of the spell on the scroll determines the spell’s saving throw DC and attack bonus, as well as the scroll’s rarity, as shown in the Spell Scroll table.

Level 1 Guiding Bolt is a +5 modifter.

Crafting Time

The general rule is:

A character must spend at least 8 hours of each day engaged in the downtime activity for that day to count toward the activity's completion.

But the Archivist's specific feature, which beats the general rule, says:

If you craft a magic item in the scroll category, it takes you a quarter of the normal time, and it costs you half as much of the usual gold.

Taken together, the reasonable conclusion would be, you need to spend the whole day crafting to produce any scrolls, but you craft up to 4 level 1 spell scrolls during that day (given enough gold and spell slots).