Spelljammer Dark Sun confirmed? Or, the mysterious case of the dissappearing Spelljammer article...

[Maxperson]

No. He has to use a focus listed in his Spellcasting trait in the Bard class writeup to cast his Bard Spells.

Doesn't matter. A bard is an arcane caster, so his focus is an arcane focus. It's just a specialized one to keep bards cool and singing stuff, rather than waving wands around. It may be listed in the class, but it is in fact a mechanic that interacts with only arcane magic.

There is no general rule which states that arcane focuses can’t be used to cast divine spells.

Yes there is.

"Arcane Focus.
An arcane focus is a special item-an orb, a crystal, a rod, a specially constructed staff, a wand-like length of wood, or some similar item designed
to channel the power of arcane spells. A sorcerer, warlock, or wizard can use such an item as a spellcasting focus, as described in chapter 10."

Per the rule on page 151 of the PHB, arcane foci channel the power of arcane spells. There is no provision there to channel divine magic, so it can't.

 

[Maxperson]

Which rules,

I've already told you multiple times. I'm not repeating it.

and where are any spells categorized this way?

This is a Red Herring that I will no longer entertain.

foci are based on Class Spell lists (and those can be broken).

Foci are by RAW not based on class lists. Page 151 of the PHB says they channel the power of arcane spells. Not wizard spells, not warlock spells, and not sorcerer spells. They are usable by those classes, but that's not what they interact with according to that rule.

 

[Parmandur]

I've already told you multiple times. I'm not repeating it.

This is a Red Herring that I will no longer entertain.

Foci are by RAW not based on class lists. Page 151 of the PHB says they channel the power of arcane spells. Not wizard spells, not warlock spells, and not sorcerer spells. They are usable by those classes, but that's not what they interact with according to that rule.

...except when they don't,which isn't even uncommon.

 

[Maxperson]

...except when they don't,which isn't even uncommon.

When doesn't an arcane focus channel the power of arcane magic when used as an arcane focus for a spell?

 

[Parmandur]

When doesn't an arcane focus channel the power of arcane magic when used as an arcane focus for a spell?

So, for a given Class, they have access to certain foci. They let them cast whatever counts as a Class Spell. No Class is really categorized as "Arcane" or "Divine," even those mentioned in that equipment bit get Subclasses that break the barrier (like Divine Soul or Celestial Pact). It's a bit of fluff, that is frequently ignored.

 

[Maxperson]

So, for a given Class, they have access to certain foci.

Not relevant. Foci are not a class ability. They are simply named in the class description for ease. Even if they WERE a class ability, that doesn't stop them from interacting with arcane magic the category, per RAW(page 151 of the PHB).

They let them cast whatever counts as a Class Spell.

No. It let's them channel arcane spells per RAW(page 151 of the PHB). Their class lists determine what arcane power they can choose to channel.

No Class is really categorized as "Arcane" or "Divine," even those mentioned in that equipment bit get Subclasses that break the barrier (like Divine Soul or Celestial Pact). It's a bit of fluff, that is frequently ignored.

Classes are explicitly given arcane or divine magic as their source.

 

[doctorbadwolf]

Doesn't matter. A bard is an arcane caster, so his focus is an arcane focus. It's just a specialized one to keep bards cool and singing stuff, rather than waving wands around. It may be listed in the class, but it is in fact a mechanic that interacts with only arcane magic.

Yes there is.

"Arcane Focus.
An arcane focus is a special item-an orb, a crystal, a rod, a specially constructed staff, a wand-like length of wood, or some similar item designed
to channel the power of arcane spells. A sorcerer, warlock, or wizard can use such an item as a spellcasting focus, as described in chapter 10."

Per the rule on page 151 of the PHB, arcane foci channel the power of arcane spells. There is no provision there to channel divine magic, so it can't.

Except the only actual mentions of arcane spells are very general, and don’t actually give any insight into what spells are arcane. Because it’s not actually a category of spell with any mechanical weight.

The rules say that those classes can use it as a Spellcasting focus. It does not even say that they can’t use it to cast spells they learned from outside that class, such as if it were to say “to cast spells on thier class spell list”. The class write ups do specify “bard spells” and the like, but not the description of the item.

Further, a Bard/Wizard cannot use a lute to cast spells they learned from their wizard levels.

Because the relevant categorization is class, not arcane or other.

 

[Parmandur]

Not relevant. Foci are not a class ability. They are simply named in the class description for ease. Even if they WERE a class ability, that doesn't stop them from interacting with arcane magic the category, per RAW(page 151 of the PHB).

No. It let's them channel arcane spells per RAW(page 151 of the PHB). Their class lists determine what arcane power they can choose to channel.

Classes are explicitly given arcane or divine magic as their source.

Well, there is a narrative distinction with a long history in the game, but as the Sage notes:

 

[Maxperson]

Except the only actual mentions of arcane spells are very general, and don’t actually give any insight into what spells are arcane. Because it’s not actually a category of spell with any mechanical weight.

That's untrue. It is a category of magic given very little mechanical weight, not none. Arcane foci mechanically interact with only arcane power. Not with wizard spells. Not with warlock spells. Not with sorcerer spells. Arcane power. That's why a wizard can give his focus to a warlock and the warlock can use it, too. Because the focus doesn't care about class lists or classes. It only cares about arcane power.

 

[Maxperson]

Well, there is a narrative distinction with a long history in the game, but as the Sage notes:

He clearly forgot about foci when he typed that. Not surprising really, given his tendency to get things wrong. He once told me I was wrong about a question of RAW on twitter, then in the sage advice his official response showed that I was correct.