D&D 5E Mirror of life trappi-EXPLOSION!

The tldr is:

Would a mirror of life trapping and a bag of holding create a gate if one were placed in the other?


Placing a bag of holding inside an extradimensional space created by a handy haversack, portable hole, or similar item instantly destroys both items and opens a gate to the Astral Plane.

This comes up because the party knows where a mjrror is and they want to carry it around in their bag of holding. They are arguing not only can the mirror be deactivated, it is only a portal to extradimensional space when hanging on a wall and a command word is spoken, but it is a different type of extradimensional space (you cannot breath in a bag of holding, but you can in a mirror of life trapping).

Does a bag of holding react with any and all forms of extradimensions? Or only those that are of the same nature as the bag of holding or "similar items"?

Shrapp Hamnier said:

The tldr is:

Would a mirror of life trapping and a bag of holding create a gate if one were placed in the other?


Placing a bag of holding inside an extradimensional space created by a handy haversack, portable hole, or similar item instantly destroys both items and opens a gate to the Astral Plane.

This comes up because the party knows where a mjrror is and they want to carry it around in their bag of holding. They are arguing not only can the mirror be deactivated, it is only a portal to extradimensional space when hanging on a wall and a command word is spoken, but it is a different type of extradimensional space (you cannot breath in a bag of holding, but you can in a mirror of life trapping).

Does a bag of holding react with any and all forms of extradimensions? Or only those that are of the same nature as the bag of holding or "similar items"?

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By RAW, it is safe to put the mirror into the bag.

That said, the DM has the final say on the matter. Just be careful not to make it a 'gotcha'. Those versed in magical knowledge should at least get an Arcana check to know about the interaction.

By my reading of the rules, you can put a mirror of life trapping inside a bag of holding just fine.

However, if the mirror traps someone who is carrying a bag, then the bag of holding has entered an extradimensional space which is created by a magic item. It's up to the DM whether mirror of life trapping is suitably similar to a handy haversack or portable hole in its use of extradimensional space as to trigger the explosion, but I think most reasonable people would agree that it is pretty dang similar. Kaboom!

77IM said:

By my reading of the rules, you can put a mirror of life trapping inside a bag of holding just fine.

However, if the mirror traps someone who is carrying a bag, then the bag of holding has entered an extradimensional space which is created by a magic item. It's up to the DM whether mirror of life trapping is suitably similar to a handy haversack or portable hole in its use of extradimensional space as to trigger the explosion, but I think most reasonable people would agree that it is pretty dang similar. Kaboom!

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I am inclined to agree to some extent, but then again, this mirror is meant more as a trap than anything else. It would be a bit of a gotcha thing if the party walked in front of the mirror and suddenly it turns into a gate sucking everyone in (also, have fun finding everything you had in it which are now scattered accross the astral plane). I see it more as an item/trap version of the demiplane spell. Which was more in tune to what I was trying to ask in that last paragraph, would a bag of holding explode the second it entered a demiplane or other forms of extradimensions? It seems like the usefulness of the bag plummets into liability-ness if it would (at least at higher levels).

Shrapp Hamnier said:

I am inclined to agree to some extent, but then again, this mirror is meant more as a trap than anything else. It would be a bit of a gotcha thing if the party walked in front of the mirror and suddenly it turns into a gate sucking everyone in (also, have fun finding everything you had in it which are now scattered accross the astral plane). I see it more as an item/trap version of the demiplane spell. Which was more in tune to what I was trying to ask in that last paragraph, would a bag of holding explode the second it entered a demiplane or other forms of extradimensions? It seems like the usefulness of the bag plummets into liability-ness if it would (at least at higher levels).

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No, a bag of holding would not explode (by RAW) upon entering a Demiplane IMO.

As you say, if a bag of holding exploded any time it encountered an extradimensional space, it's value would be much diminished. It would be more of a liability than an asset in many cases, since by that reasoning you couldn't bring it inside a rope trick, and good luck if you were to get nailed by a banishment spell under such a house rule.

The explosive interaction specifically lists bags of holding, heward's handy haversacks, portable holes, and similar items. How do we define similar item? What do they all have in common? They are used primarily to carry extra gear. Does a mirror of life trapping allow one to carry extra gear? Technically, if one got really creative with it it could (load a kobold up with all your spare gear and trap it inside), but that's not it's primary purpose. It's a magical trap/prison. Unless the primary purpose of the magic is to allow you to carry extra gear, I would be inclined to say that the magic isn't similar enough for the purposes of the exploding. I would guess the reason for this is (beyond simply that that's the way it's always worked) that the designers didn't want people carrying near infinite gear by nesting bags of holding inside other bags of holding ad infinitum.

Shrapp Hamnier said:

I see it more as an item/trap version of the demiplane spell. Which was more in tune to what I was trying to ask in that last paragraph, would a bag of holding explode the second it entered a demiplane or other forms of extradimensions? It seems like the usefulness of the bag plummets into liability-ness if it would (at least at higher levels).

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Well, that's a really good point.

My only qualm is that now I don't quite see the distinction between all the extradimensional spaces. It would seem at first glance that the main difference is that portable hole and bag of holding are contiguous with the material plane -- that is, you can enter the extradimensional space without traversing a "portal" or just teleporting in. Mordenkainen's magnificent mantion specifically mentions a portal, but demiplane talks about a "shadowy door" and rope trick talks about an "invisible entrance." Those are a bit more iffy; I think it's somewhat reasonable to rule that the bag of holding explodes when it enters a rope trick, which is a somewhat similar pocket of space.

I think [MENTION=53980]Fanaelialae[/MENTION] had the best answer in his first post -- if the DM can work out the interactions, then the PCs should be able to figure it out pretty easily, too. If the bag of holding is going to become a walking deathtrap, there could even be tactile feedback when you try to put it into a dangerous extradimensional space -- like a slight repulsion, and you have to force it in.

77IM said:

Well, that's a really good point.

My only qualm is that now I don't quite see the distinction between all the extradimensional spaces. It would seem at first glance that the main difference is that portable hole and bag of holding are contiguous with the material plane -- that is, you can enter the extradimensional space without traversing a "portal" or just teleporting in. Mordenkainen's magnificent mantion specifically mentions a portal, but demiplane talks about a "shadowy door" and rope trick talks about an "invisible entrance." Those are a bit more iffy; I think it's somewhat reasonable to rule that the bag of holding explodes when it enters a rope trick, which is a somewhat similar pocket of space.

I think [MENTION=53980]Fanaelialae[/MENTION] had the best answer in his first post -- if the DM can work out the interactions, then the PCs should be able to figure it out pretty easily, too. If the bag of holding is going to become a walking deathtrap, there could even be tactile feedback when you try to put it into a dangerous extradimensional space -- like a slight repulsion, and you have to force it in.

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This is all kimd of what I was thinking. Perhaps more than the distinction of portals, I was thinking the ability to breath within the dimension. All the spaces that talk about exploding if within each other mention that creatures suffocate if inside for too long. My interpretation of this that the dimension is less complete than others such as mordenkain's places or demiplanes, still stable enough for general use, but so much that they can overlap.

This has been tremendously helpful all. I had my thoughts and ideas, but I wanted to be sure I wasn't overlooking something (not so) obvious about how dimensions - bags of holding more specifically - work.