In previous editions a Magic Mouth spell could not be used to trigger an object, but in 5e it's not quite as clear.

I'm designing a scenario where a crew of thieves enter a Mirror of Life Trapping, which then has a magic mouth spell cast on it and is locked in the vault of an art gallery. Their scheme is to have the magic mouth trigger at midnight, speaking the words to release the thieves so they can loot the vault.

In the PHB description for magic mouth, it states:

When that circumstance occurs, a magical mouth appears on the object and recites the message in your voice and at the same volume you spoke.

As far as the DMG, the relevant section in the Mirror of Life Trapping description says:

While within 5 feet of the mirror, you can use an action to speak the name of one creature trapped in it or call out a particular cell by number.

Clearly the magic mouth is not using an action, but outside of combat are actions really "spent" or is it just a measure of time?

Does anyone know of an official 5e ruling on this, or can you make a case either for or against it? It's for possible publication in a DM's Guild adventure, so I don't want to rely on DM fiat if I can help it.


2 Answers 2


It is likely that the user of a magic item must be a creature and thus that this would not work

The rules on actions are specifically the rules on "Action in Combat" and so outside of combat we fall back onto the general guidelines found on page 6:

  1. The DM Describes the environment.
  2. The players describe what they want to do.
  3. The DM narrates the results of the adventurers' actions.

And so it would seem that whether the magic mouth can use command words would be left up to the DM as they dictate the results of the actions.

There is no rule stating that only creatures can take actions, in fact, sentient magic items can have actions of their own. It is usually just impossible for an object to take an action but a magic mouth would perhaps be able to take actions that rely on speaking such as command words.

The section on "Activating a Magic Item" states:

Activating some magic items requires a user to do something in particular, such as holding the item and uttering a command word...
A magic item that requires the user to speak a command word

User (pun not intended) @slagmoth pointed out that when most people hear the word "user" they would assume a person and thus a creature, or at least not an object. If a user must be a creature this would automatically prevent magic mouth (and other objects) from being able to activate magic items including the Mirror of Life Trapping. This is strongest evidence that the magic mouth cannot do this.

Unfortunately items with command words use the word "you" when describing their activation. The word clearly does not mean only one specific person can control the mirror, instead anybody that knows its command words can manipulate the mirror. "You" is a general enough pronoun that it perhaps could include the magic mouth; However, it is clear that the person the magic mouth is replicating would not be activating the item, it would be the mouth itself. This is supported by the fact that magic mouth cannot provide the verbal components of a spell because verbal components are required to be said by the caster.

There is at least one problem that results from allowing the magic mouh to activate magic items:
If a magic item has a command word that cast a concentration spell typically the user of the magic item would be concentrating on the spell but in this case the magic mouth itself would have to be concentrating on the spell.

Though activating a magic item does not explicitly require the user to be a creature, attuning to a magic item does (DMG page 138):

Some magic items require a creature to form a bond with them before their magical properties can be used...
Without becoming attuned to an item that requires attunement, a creature gains only its nonmagical benefits...
Attuning to an item requires a creature to spend a short rest focused on only that item...
[T]he creature gains an intuitive understanding of how to activate any magical properties of the item, including any necessary command words...

The fact that attuning to a magic item, the method of learning its command words, requires one to be a creature is slight evidence that objects are not intended to activate magic items, but it does not help us in terms of using the actual available text.

Finally there is one particular line in the Mirror of Life Trapping's description which may provide evidence that a mouth cannot activate the mirror:

Any creature other than you that sees its reflection in the activated mirror...

In a standard English reading this would imply that "you" refers to a creature but it does not explicitly require this to be the case so this argument is very slight.

Overall we have three pieces of evidence pointing towards the magic mouth not being allowed to do this:
A user is unlikely to be interpreted so that objects qualify.
This would create some odd scenarios such as having a magic mouth concentrate on spells cast from magic items.
Attunement, a related mechanic, explicitly requires one to be a creature.

  • \$\begingroup\$ In support of your answer, I checked the SA Compendium and it is silent on the details of the mirror or life trapping / magic mouth. \$\endgroup\$ Commented Aug 23, 2019 at 16:23
  • \$\begingroup\$ @KorvinStarmast Yeah Crawford has never even tweeted about magic mouth once to my surprise \$\endgroup\$ Commented Aug 23, 2019 at 16:24
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    \$\begingroup\$ Just a minor point and it may not affect this answer but a "user" is a "person" in standard English, personally I would just extend that to creature, which in my games would exclude spell effects from meeting that criterion. \$\endgroup\$
    – Slagmoth
    Commented Aug 23, 2019 at 17:28

The magic mouth IS the user. Its the user's spell as well as their voice. I would allow it. It is a clever use of items that I would never penalise a party for coming up with. However the second time they tried it the bank would cast remove magic on all deposits...

  • 1
    \$\begingroup\$ By "remove magic", do you mean the dispel magic spell? \$\endgroup\$
    – V2Blast
    Commented Aug 24, 2019 at 7:19

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