Does the AC bonus from Bracers of Defense stack with the AC calculation from the mage armor spell?
I'm asking this because there is some contention behind the ruling of this combo, between two designers. In 2016, Mike Mearls states that they do not.
However, in 2017, Jeremy Crawford says the opposite. Twice, in fact.
I also question whether donning the Bracers of Defense counts as putting on armor, as the mage armor spell stipulates that donning armor will dismiss the spell. In my opinion, it does not, as the bracers are classified as a Wondrous Item, not as an armor piece, despite actually being a piece of armor. For reference, here are the item/spell quotes:
While wearing these bracers, you gain a +2 bonus to AC if you are wearing no armor and using no shield.
You touch a willing creature who isn't wearing armor, and a protective magical force surrounds it until the spell ends. The target's base AC becomes 13 + its Dexterity modifier. The spell ends it if the target dons armor or if you dismiss the spell as an action.
How should our DM rule this, RAW?
Best Answer
Yes, they do stack
Jeremy Crawford is the official rules arbiter for 5e, not Mike Mearls. Even so, the response by Mearls that you linked misunderstands what the Bracers of Defense do. Mearls' response:
As the replies to his tweet point out, the description of the Bracers of Defense says "you gain a +2 bonus to AC"; they don't provide a different AC calculation, so the two do stack.
Bracers aren't armor
First of all, to point out the obvious: if bracers were considered armor, the Bracers of Defense would never provide any benefit because they'd disqualify their wearer from gaining their own benefit.
Secondly, bracers in general are not considered armor. The only things considered armor (besides the "natural armor" of some creatures) is the list of items on the Armor and Shields tables, or an item that is otherwise listed as being armor. Shields are not armor, and neither are wondrous items.
The Bracers of Defense are listed as a wondrous item. Wondrous items are their own separate category, as Jeremy Crawford confirms here (in response to a question about whether druids can use the Bracers of Defense):
(In fact, the "wondrous item" classification is specifically applied to magic items that are neither weapons nor armor. Any magical equipment that doesn't fit into either of those two categories is listed as a wondrous item.)
Bonuses always stack unless they're from duplicates
As Jeremy Crawford points out here: