Can a Glamour bard cast a level 1+ spell and cast the Command spell using the Mantle of Majesty feature in the same turn?

Question

For clarity

It's already clear from several other questions that a Glamour bard may not maintain concentration on Mantle of Majesty and another concentration spell at the same time. This is not my question.

Rules

A creature may not normally cast 2 spells of 1st level or higher in the same turn, even if one is an action and the other is a bonus action. They may maintain concentration and cast a level 1+ spell that does not require concentration. They may also cast a cantrip and a level 1+ spell.

The question

Does the Glamour bard's "free" casting of the 1st-level spell command as a bonus action granted by the Mantle of Majesty feature qualify as a spell of 1st level or higher, preventing the bard from casting another spell of 1st level or higher, such as charm person or dispel magic, on the same turn?

My thoughts

I suspect it does not, as most abilities such as martial moves, ki, or breath weapons are not treated as spells. However. I have not found any defense for this in any of the rulebooks.

Answer 1

You are effectively asking if a spellcast that is granted by a class feature that is not the Spellcasting feature is subject to the "only one non-cantrip spell may be cast per turn rule."

The answer is that it is and therefore you may not.

The rule for casting a bonus action spell states:

A spell cast with a bonus action is especially swift. [...] You can't cast another spell during the same turn, except for a cantrip with a casting time of 1 action.

This is a blanket statement that doesn't care about the source of the spell. It does not matter if the spell is cast as a result of a magical item, the slots granted by the Spellcasting feature, or some other class/race feature.

If you, by whatever means, cast a bonus action spell, you may only cast a cantrip with your action.

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There is a caveat to this.

Sometimes there are class features that say they produce an effect without mentioning the phrase "you cast" and conclude with the phrase "as if you were concentrating on a spell." So long as the words "you cast" are not used, the ability is not a spellcast.

For example, the Archfey Warlock's Dark Delirium ability:

[...] as an action, choose a creature that you can see within 60 feet of you. It must make a Wisdom saving throw against your warlock spell save DC. On a failed save, it is charmed or frightened by you (your choice) for 1 minute or until your concentration is broken (as if you are concentrating on a spell).

Though it functions very similar to one, this is not a spell because the ability does not say that the Warlock is casting anything. It merely borrows the same concentration mechanic from those kinds of spells to serve as a possible way for the effect to end.

You have to be careful not to get lured into thinking that the phrase "as if you were concentrating on a spell" means it's not a spell in all cases. It's important to read the full description of the ability. For example, your Mantle of Majesty also includes the phrase "you cast".

It does this because, in addition to casting Command, the ability tacks on the added benefit "you take on an appearance of unearthly beauty for 1 minute" and it's clarifying that this extra benefit also ends when you lose concentration.

Another thing you might see: some abilities/features use the phrase "as if you had cast" such as the magical item Ventilating Lungs and its gust of wind ability. This phrase indicates that you are not casting a spell but achieving the same effect as if you were.

Answer 2

It counts as a bonus action spell, and thus you cannot cast another leveled spell on that turn

The language of the feature is fairly clear:

As a bonus action, you cast command...

Since you are casting a spell as a bonus action, you would be unable to cast leveled spells as addressed in this Q&A and in the Basic Rules:

You can't cast another spell during the same turn, except for a cantrip with a casting time of 1 action.

The reason features such as maneuvers, most ki features¹, and breath weapons don't interact with this rule is because you are not casting spells as a bonus action.

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¹ There is one ki feature that does cast a spell as a bonus action: Searing Arc Strike of the Way of the Sun Soul. This would similarly prevent any other leveled casting for that turn.