Can you use Sublime Chord spell slots to cast Bard spells known from your Bard class (or vice-versa)?

Question

Question is lengthy, so I'll put the question again but in full here:

Can you use Sublime Chord spell slots to cast Bard spells known from your Bard class (or vice-versa)?

Obviously the spell would have to be level 4-6.

We've got a bard looking at taking levels in Sublime Chord (he's already a level 17 bard, so he has a lot of spells as a bard already), and Greater Mirror Image is an awesome spell. They are on both the Bard and Sor/Wiz lists at level 4.

My guess is no, and that the rules weren't intended to work that way. We were saying it might be worth it to get it as a known spell for both classes. However, Bard and SC cast using the same mechanics, so it seems rather open to interpretation, and it seems strange to have to learn the same spell twice in this particular case (see below). I was wondering if anyone else had any resources or links to rulings on this.

The main argument is that from the perspective of almost any other set of 3.5 casting mechanics, you shouldn't be able to do it. However in the case of Bard/SC, it seems unreasonable that you should have to learn a level 4 bard spell to cast it as a bard, then learn the same spell again (as a bard spell as required by the sublime chord spellcasting descriptor) just to cast it as a sublime chord.

Answer 1

No.

Sublime chord spell slots are used to cast sublime chord spells, of which a sublime chord knows a limited number as given in the table. Those spell slots cannot be used for any other classes’ spells, whether known or prepared.

This isn’t precisely spelled out anywhere, though. The closest we get is

The [multiclassed] character gains spells from all of his or her spellcasting classes and keeps a separate spell list for each class. If a spell’s effect is based on the class level of the caster, the player must keep track of which class’s spell list the character is casting the spell from.

^{(Classes > Multiclassed Characters > Spells)}

If you’re a bard or sorcerer, you can select any spell you know, provided you are capable of casting spells of that level or higher.

[...] If you’re a bard or sorcerer, casting a spell counts against your daily limit for spells of that spell level, but you can cast the same spell again if you haven’t reached your limit.

^{(Magic Overview > Casting Spells > Choosing a Spell)}

It’s a synthesis of these two rules that says that in order to cast a spell, you have to know it and it counts against your daily limit, and that the spells you know and your daily limits for casting spells are specific to each class you have levels in and are kept separate.

Certainly, there is nothing special about the sublime chord that changes this; though the sublime chord has an unusual way of calculating its caster level that depends on levels in other arcane spellcasting classes, it doesn’t otherwise “combine” spellcasting with any previous class.

Generally speaking, since the sublime chord requires 3rd-level spells, and then offers spells of 4th level and up, it isn’t supposed to matter much, because you aren’t expected to have 4th-level bard spells. True, sublime chord does require 10 HD before you can meet its skill requirements, and a 10th-level bard does just barely have 4th-level spells, but sublime chord is a pretty good reason to multiclass for two or three levels.

All that said, I would probably allow it, for the hypothetical 10th-level bard/\$x\$th-level sublime chord.