Can an Armorer Artificer get around the Armor Model feature's limitation of changing models after a short/long rest by swapping in different armor?

Question

At 3rd level, the Armorer artificer gains the Armor Model feature, which allows a choice between Guardian and Infiltrator models (TCoE, pg. 16).

Because the former is good for all-out melee but the latter is intended for range and stealth, I was exploring the idea of using different base armors for each of these: heavy armor for Guardian (maximum AC of 18, disadvantage on stealth – i.e. plate armor), and medium or light for Infiltrator (maximum AC of 16 or 17 when not accepting disadvantage on stealth – i.e. breastplate or studded leather armor).

An Armorer can't have two sets of Arcane Armor active simultaneously, so I needed to figure out what it would take to change from one to the other.

According to the Arcane Armor feature (TCoE, pg. 15-16):

[...] As an action, you can turn a suit of armor you are wearing into Arcane Armor, provided you have smith's tools in hand.

You gain the following benefits while wearing this armor:

• [...]
• You can [...] doff the armor as an action.

Furthermore, the table on page 146 of the Player's Handbook indicates how long it takes to don normal armor:

• Light armor: don in 1 minute
• Medium armor: don in 5 minutes
• Heavy armor: don in 10 minutes

So changing out of heavy Arcane Armor and into medium Arcane Armor would take: 1 action (doff heavy Arcane Armor) + 5 minutes (don normal medium armor) + 1 action (convert normal medium armor to Arcane Armor) = 5.2 minutes. In general:

Swapping any normal armor in for existing Arcane Armor takes 2 actions plus the time needed to don the normal armor.

This struck me, because it seemed to be a shortcut for swapping between Armor Models. Normally, the Armor Model feature specifies that you can do so when you finish a rest (TCoE, pg. 16):

You can change the model whenever you finish a short or long rest, provided you have smith's tools in hand.

Yet it seems like having a second set of normal armor available (of any class) allows you to change models in either 1.2, 5.2, or 10.2 minutes, instead of the 1 hour required by a short rest.

Now, because an artificer can only activate infusions after a long rest, any infusions on the former Arcane Armor must stay with it until at least the end of the next long rest, but this sacrifice might be worth it if you're in a dreadful rush and you really want the model you don't currently have. And you might even have one infusion "pre-loaded" in armor you'd set aside to be swapped in.

Is my logic sound? Or have I missed something that would disallow this shortcut?

Answer 1

Short Answer: No, this doesn't work

The description of the Arcane Armor feature (TCoE, p. 15-16) describes how to make normal armor into Arcane Armor, its benefits, and when a suit of armor will cease to be Arcane Armor. Notably, it does not say that you can choose a model at the moment of conversion.

In other words, until a suit of Arcane Armor is modified using the Armor Model feature (which says it can be used whenever finishing a short or long rest, and gives no other options for when it can be used), it will only give the "base" benefits described in Arcane Armor, rather than any of the specialized benefits from a model.

Answer 2

Frame Challenge: You are an artificer; solve problems like this one with class abilities

Since you are an Artificer, rather than trying to find a strange edge case that lets you save 40-50 minutes when switching between models (and also requires you to lug around a spare suit of armor), use your artificer class abilities to build a multi-purpose Arcane Armor. If it is that important for you to be able to switch models 'on the fly':

Apply Stealth Features to your Guardian Armor
Start with a Heavy Armor in your guardian model. On any day that you think you might need to rapidly change into Stealth mode, Infuse the armor itself or a separate item with Replicate Item:Boots of Elvenkind or a Replicate Item:Cloak of Elvenkind. Note that the Boots don't require attunement, so you can loan these out to your party scout and when you want to use them, spend only as much time as they need to take them off and you to put them on. [Note: this requires you to be at least 6th level]

or

Apply Shield Features to your Infiltrator Armor
Start with Heavy Armor in your infiltrator model (since your built-in Dampening Field already cancels the disadvantage on Stealth), or the best AC Medium armor (if you actually want Advantage on Stealth, not just lack of Disadvantage). On any day that you think you might need to rapidly change into Shield mode, Infuse the armor itself or a separate item (shield) with Enhanced Defense. Note that a shield won't require attunement, so you can loan this out to your party tank and when you want to use it, spend only as much time as they need to pass it to you. Save a spell slot for mirror image and prepare blur. [Note: this requires you to be at least 5th level]

Answer 3

Yes, this technically works by RAW, but check with your DM.

The logic here is sound, with it mainly revolving around the following quoted section of the Arcane Armor feature (TCoE, p. 15-16):

[...] As an action, you can turn a suit of armor you are wearing into Arcane Armor, provided you have smith's tools in hand.

Since no limit on how often or when this action can be taken, it is assumed by default that it can be taken as often as the player would like.

However, there are two other quotes to take into consideration here that should be noted. First, from the Arcane Armor feature:

The armor continues to be Arcane Armor until you don another suit of armor or you die.

And second, from the Armor Model feature (TCoE, p. 16):

You can change the armor's model whenever you finish a short or long rest, provided you have smith's tools in hand.

So, when these quotes are combined, while they do not contradict the prior logic, they do show a different intent behind the rules. Since you can only have one set of Arcane Armor at a time (that being the one you're wearing), and it's stated that you can change it after a short or long rest, it would seem to imply that you are meant to stick to just the one suit of armor, which you then can switch during a rest.

As such, it would likely still be prudent to check with your DM whether this would be okay to use, since it seems to be moreso a loophole than an intended function of the rules.

Answer 4

This doesn't work because you don't automatically get to change the Armor Model when creating new Arcane Armor.

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All Arcane Armor gets the benefits of an Arcane Model.

The Arcane Model feature begins by saying:

You can customize your Arcane Armor.

This places no restrictions on when the customization can take place, so new Arcane Armor does get the benefits of an Arcane Model.

However, the Arcane Model can only be changed after a rest.

As the original question referenced, Arcane Model says:

You can change the model whenever you finish a short or long rest, provided you have smith's tools in hand.

It does not say you can change the model whenever you create a new set of Arcane Armor — although, of course, if you create new Arcane Armor when finishing a rest, changing the model can effectively happen at the same time.

Therefore the active Arcane Model carries over to new Arcane Armor.

Once an Armor Model has been assigned, that assignment remains active — even through the creation of new Arcane Armor — until it's changed when finishing a rest.

There is a way for this to make narrative sense.

For an in-game justification, simply assume that the parts used to create model-specific features must be repurposed when creating a different model.

For example, if an artificer changes Guardian Arcane Armor on a splint armor base to Guardian Arcane Armor on a half plate base, they need only transfer the Guardian's customizations from the splint armor to the half plate. They don't have to recreate those customizations from scratch.

However, if they want to change from Guardian model to Infiltrator model, they must scavenge from parts that are Guardian-specific in order to make the new parts that are Infiltrator-specific. Perhaps they must remove magical crystals from the Thunder Gauntlets and use them to power the Lightning Launcher. Maybe they must alter a field generator so it creates the Dampening Field instead of the Defensive Field.

Whatever the details, this is a more involved process, so it can only happen (with smith's tools) when finishing a rest.