The description of the Amulet of the Black Skull from Tomb of Annihilation says, in part:

[...] You can use an action to expend 1 of its charges to transport yourself and anything you are wearing or carrying to a location within 100 feet of you. The destination you choose doesn’t need to be in your line of sight, but it must be familiar to you (in other words, a place you have seen or visited), and it must be on the same plane of existence as you.

Since the item description already specifies that the location must be "within 100 feet of you", saying that the location "must be on the same plane of existence as you" seems redundant.

Are there any situations when this is definitively not a redundancy?

I’ve never played Tomb of Annihilation; is there an adventure-specific circumstance I’m not aware of that makes it necessary to specify both restrictions in the description of the item?

  • \$\begingroup\$ I’m voting to close this question because it actually is three questions, the first of which ('Why does the description...') is asking for the designer intent of the amulet. \$\endgroup\$
    – Kirt
    Commented Feb 5, 2022 at 6:51
  • 1
    \$\begingroup\$ @Kirt This is not a design intent question. I don’t care one bit what the authors have to say about this. I’m looking for rules interactions or historical events from the lore that demonstrate that the magic item description is not redundant. As in, “Why does the description…?”, “Because if it didn’t, you would be able to ______”, or, “Because in 1483 Drizzt did _______”. \$\endgroup\$ Commented Feb 5, 2022 at 10:11
  • \$\begingroup\$ @Kirt If you really want extended discussion on this you can put it up on meta. \$\endgroup\$ Commented Feb 5, 2022 at 16:23
  • 2
    \$\begingroup\$ I didn't say you asked what the authors said. The second and third questions ask about the objective effects of the amulet's description and are fine. The first question presumes that there is a reason for the apparent redundancy in the description and then asks why it is there. That is the definition of a designer intent question - it is asking why the description was written as it was and invites opinion-based speculation as to the answer. \$\endgroup\$
    – Kirt
    Commented Feb 5, 2022 at 17:12

1 Answer 1


Distances between planes are ill-defined in D&D 5e

As I cover in this answer, the rules do not clearly spell out how to compute the distance between two points on different planes. However, there are several places where the rules appear to assume that such a definition exists, such as the Wand of Enemy Detection (emphasis added):

For the next minute, you know the direction of the nearest creature hostile to you within 60 feet, but not its distance from you. The wand can sense the presence of hostile creatures that are ethereal, invisible, disguised, or hidden, as well as those in plain sight.

There would be no reason to mention detecting enemies within 60 feet on another plane if distances between the material and Border Ethereal were undefined, and yet a definition for inter-planar distance is never provided by the rules.

There are several other places in the core rules that mention something like this, and it seems that the passage quoted in the question is another such example. Explicitly disallowing planar travel entirely sidesteps the issue of whether inter-planar distances are defined.

  • \$\begingroup\$ +1. Just a little question / suggestion, in older editions tgere were places where you could just walk to another plane. If it is still the case it adds up to the distance issue. But is it? \$\endgroup\$
    – Mołot
    Commented Jun 20, 2020 at 8:00
  • \$\begingroup\$ @Mołot If you're looking through a literal portal to another plane, the same issue applies: distance between points in different planes isn't really defined. \$\endgroup\$ Commented Jun 20, 2020 at 14:45
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    \$\begingroup\$ Distances between the Border Ethereal and the planes it touches are precisely defined. From the DMG: "The Ethereal Plane is a misty, fog-bound dimension. Its "shores," called the Border Ethereal, overlap the Material Plane and the Inner Planes, so that every location on those planes has a corresponding location on the Ethereal Plane." Because every location on the EP has a corresponding location on an IP, the distance between a place on an IP and a place on the EP is precisely the distance to the place on the IP to which the EP corresponds. It is that distance which limits the WoED. \$\endgroup\$
    – Kirt
    Commented Feb 5, 2022 at 15:54
  • \$\begingroup\$ @Kirt: just because every location on the EP has a corresponding location on the IP doesn't mean that the distances between two places on the IP and their corresponding places on the EP are the same. Consider laughingsquid.com/… that (purportedly) shows the size of US states by population rather than geographical size (or mapping N to N-squared, 2->3 is much closer than 4->9, and 7 doesn't have a whole-number root). Is there evidence that the geography of the two planes is identical, beyond just that every EP location has an IP location? \$\endgroup\$
    – minnmass
    Commented Feb 22, 2022 at 15:34
  • \$\begingroup\$ @minnmass The easy response is parsimony - do you have any evidence to suspect that the planes have a different geography? If there is some strange scaling factor involved, how do you suggest the rules work for spells and abilities that measure distances from objects on the prime to those in the ethereal? The more complicated response is that, unlike numbers, I am assuming that 'locations' have a minimum size and are discrete - but that is more philosophical and I don't have the maths background to explain what I mean there. \$\endgroup\$
    – Kirt
    Commented Feb 22, 2022 at 16:12

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