Do Multiclass Spellcasters Have To Spend Additional Spell Slots?

Question

The Magic Initiate Feat has a restriction of "Once you cast [this spell], you must finish a long rest before you can cast it again". Some have argued that this prevents you from casting the spell more than once per long rest, even if you can already cast the spell from some other feature.

This made me wonder if this line of reasoning is applicable elsewhere. Were there any other situations where being able to cast a spell from multiple sources imposed a net restriction on your ability to cast it? I came up with the following scenario to demonstrate.

Take for example, a multiclass Shadow Monk/Arcane Trickster who has learned the Darkness spell from their Arcane Trickster subclass.

The Shadow Monk's description says:

PHB 80: As an action, you can spend 2 ki points to cast darkness, darkvision, pass without trace, or silence, without providing material components.

The Arcane Trickster's description says:

PHB 98 To cast one of these spells, you must expend a slot of the spell's level or higher

Therefore, if the character spends 2 ki points to cast Darkness, and Darkness is one of their Arcane Trickster spells, they must also spend a spell slot on top of the 2 ki points.

Is there any flaw in my reasoning? This conclusion seems nonsensical to me, but if you accept the above interpretation of Magic Initiate, is there any reason to rule otherwise?

Answer 1

If you want a written ruling on your question, you can go to the description of Spell Slots (PHB p 201):

Some characters and monsters have special abilities that let them cast spells without using spell slots. For example, a monk who follows the Way of the Four Elements [...] can cast spells in such a way.

So in your example, spells cast using the Shadow Arts feature expressly do not consume spell slots.

As far as Magic Initiate, the exact wording is (emphasis mine):

Once you cast it, you must finish a long rest before you can cast it again.

This becomes a bit Clintonesque if you're the right age, but "it" could have a few definitions:

• All instances of that spell, which seems to be how you are interpreting it
• The spell you learned through the feat Magic Initiate, but not instances of the spell acquired by another means
• The casting of the spell at its lowest level without consumption of a spell slot, which was granted to you by the Magic Initiate feat, but not any other means you might have of casting the spell

There is nothing I can find in the text that would indicate that the first definition is unambiguously correct. You can, of course, play it however you would like, but the more restrictive interpretation is no more supported by the rules than the one more in line with the apparent intent of the ability.

Answer 2

This would be silly.

Here's the thing, under multiclassing it reads as follows:

Each spell you know and prepare is associated with one of your classes, and you use the spellcasting ability of that class when you cast the spell.... (PHB 164)

So in effect, Darkness (monk) and Darkness (Arcane Trickster) are two completely different spells. You use different spell casting abilities and foci when you cast them (though with darkness in particular there is no save/attack to deal with the ability). But you would not consume both and arcane trickster spell slot and have to spend Ki points to cast them, because they are effectively different spells.

This is how all multiclassed spells work. If you have the same spells on two lists, you choose which one you are casting from. Say if you were a Bard|Cleric and you had prepared Bane as both a Cleric and a Bard spell. You would not have to spend a spell slot from each class to cast it (that would be silly, it's one spell, and spell slots are shared between classes). You'd choose whether you were casting it as a Bard or Cleric spell, and that would dicate whether save DC was calculated with Charisma or Wisdom (Respectively).

Similarly in your example, if we say took a Wizard Monk and they wanted to cast Thunderwave. They could either spend 2 Ki points and cast it via Fist of Four Thunders or use a spell slot to cast it as a Wizard spell. If cast with the ki points it would use Wisdom for the save DC. If they wanted to cast it as the wizard spell, it would use intelligence.

In conclusion, all spells learned from an MC are tied to the specific class, and as such, only burn the resources of the class it was acquired from. If there is any duplication, it is handled by selecting which resource you are consuming, and if there is overlap, which class you are casting it from.

Answer 3

No. If a character has the ability to cast a particular spell from two or more different sources, then the character has to choose which source is used to cast the spell when they decide to cast it. So in your example situation with the Shadow Monk / Arcane Trickster the the character must decide whether to cast the Shadow Monk variant or the Arcane Trickster variant and then meet whatever restrictions or requirements dictated by the chosen variant. If you choose to spend the Ki points and cast Darkness using your Shadow Monk mojo, ignore the spell slot cost imposed by Arcane Trickster. On the other hand, if you want to save the Ki and cast Darkness as an Arcane Trickster, then you have to cough up a spell slot.