Can a magic item require attunement twice?

Question

Can an item require attunement twice to be used?

NOTE: This question is a revisit of an existing question: Can an armblade require double attunement if it integrates a magic weapon that normally requires attunement?

After the release of Eberron: Rising from the Last War, the focus of this question (the armblade magic item) changed and no longer had the specific trait being questioned in it, and as such this is simply a revised version of that question.

The question is simple: Can an item require attunement twice? Currently, all official magic items simply "require attunement", but is there a possibility of an item requiring it twice?

One example of this would be something such as the prosthetic limb or armblade, where the item is integrated into one's body which is what creates the requirement for attunement. However, if one of these items is enchanted with something that would normally require attunement, would this cause them to require attunement twice?

Alternatively, a character might try to combine 2 items into 1 in order to gain benefits from both at the same time, but if both of those items required attunement, would the new item require attunement twice to get both benefits?

Answer 1

Dungeons & Dragons has a general principle that specific rules override general rules (see page 7 of the Player's Handbook and the introduction to the Basic Rules). That means that if the designer of a magic item wants it to take up two attunement slots on a character, they can have the specific rules for that item override the the general rules that say that you can attune up to three different items.

An example of this general idea (that a specific rule can modify the general attunement rules) already exists, as the Artificer class published in the recent Eberron books (though not the Unearthed Arcana playtest version). An Artificer gets extra attunement slots at levels 10, 14 and 18.

There are probably a few different ways a rule to require double attunement could be phrased. The item could simply say that it counts as two items for attunement:

This item requires attunement twice before its magical properties apply. It counts as two attuned items for a character who attunes to it twice.

Or it could modify the rules about how many items the attuning character can attune to at the same time (while only taking up one slot itself):

This item requires attunement. While attuned to this item, the number of items you may be attuned to is decreased by one (usually from three to two). If this reduction would mean you would be attuned to too many items, your attempt to attune to this item will fail.

Of course, that phrasing assumes that the item is beneficial to the wielder, and that the extra attunement slot cost is a trade off for some really good positive effects. If it's a cursed item however, there could be other ways to phrase the magical effects that are more explicitly bad:

Curse: When you attune to this item, the number of items you may be attuned to is decreased by one (usually from three to two). If this reduction means you would be attuned to too many items, your attunement to one of your other items ends immediately. You may choose which item loses attunement, though this effect will not break any other curses. You may not remove or end your attunement to this item until you are targeted by Remove Curse or similar magic.

All of these examples are just things I made up. It may be that no official item published by Wizards of the Coast will ever monkey with attunement the way I have suggested. But that doesn't mean you can't do so for your own game. As long as the rule makes sense to you and the other players at your table, there's no reason not to include it if you think it would be fun.

Answer 2

An item can be attuned to more than once, but it doesn't count against the 3 attuned items rule

Attunement is something that an item either requires, or it doesn't. This is proven by the wording of the text on attunement in the DMG:

An item can be attuned to only one creature at a time, and a creature can be attuned to no more than three magic items at a time

(emphasis mine)

This specifies that you can be attuned to 3 magic items at a time, not have 3 attunements active at a time. As such, it would seem that attunement is just something that an item either has, or that it doesn't.

However, technically, there is nothing still explicitly preventing still having an item need attunement twice, and there is still one aspect of attunement that would be applied to this: the time required to attune

Attuning to an item requires a creature to spend a short rest focused on only that item while being in physical contact with it

So technically, an item could require attunement more than once, but the only change is that it takes longer to attune to

(NOTE: Thanks to @Someone_Evil for the original version of this answer)