Ykhjuy

In my campaign, my players were very close to accidentally freeing Tiamat from her prison in the Nine Hells (long story). However, they ended up averting disaster and not summoning her.

However, should they have summoned her, my players had a plan which they told me about afterwards. If Tiamat were to ever appear, they planned to place a Bag of Holding next to her, and then use Mage Hand to place another one inside of it, causing this effect:

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. The gate originates where the one item was placed inside the other. Any creature within 10 feet of the gate is sucked through it to a random location on the Astral Plane. The gate then closes. The gate is one-way only and can't be reopened.

Now, setting aside the difficulty of actually getting that close to Tiamat in the first place, is this something that would actually work? I'm inclined to believe not, since:

• Tiamat is enormous, and would not be fully within the 10 ft radius of the gate created.


• On her stat block from Rise of Tiamat, she has Limited Magic Immunity to spells level 6 and under. Since a Bag of Holding is an uncommon magic item, it would make sense to be immune to this effect as well.


• She's a minor deity, so she gets a pass on things like this.

Despite these points, I can't actually find anything definitively within RAW that supports my claims. Is it possible to send Tiamat to the Astral Plane using this strategy?

RAW, there's no reason it wouldn't work

Tiamat is enormous, and would not be fully within the 10 ft radius of the gate created.

RAW typically consider a creature to be affected by effects that overlap with it despite them not engulfing the creature fully. Eg. a fireball deals full damage even if it touches just the corner tile of a gargantuan creature.

On her stat block from Rise of Tiamat, she has Limited Magic Immunity to spells level 6 and under. Since a Bag of Holding is an uncommon magic item, it would make sense to be immune to this effect as well.

The Astral Tear is not a spell, so spell immunity doesn't help against it.

She's a minor deity, so she gets a pass on things like this.

She doesn't have such protection by the rules, although it's a sensible house ruling. I'm not sure if I would enforce it myself. However...

Tiamat could probably escape quite fast

Tiamat herself lacks any ability to shift through planes, but her raw power is still enough to make her an apex predator in the Astral plane. Her extremely high Intelligence score also allows her to move faster than most creatures in there. It probably wouldn't take her long to find a creature who knows their way around the Astral Plane and the planar gateways and gently persuade said creature to allow Tiamat back from the Astral Plane. Given the potential utility of befriending a god, I wouldn't be surprised if such a creature even sought her out!

It could well be a matter of days, perhaps weeks, but assuming the party can't find a new pair of Bags of Holding by then, they'll be facing one angry Dragon Goddess once she makes her way back...

It should work. For a while.

You raised the main issues.

• On the size issue. Tiamat doesn't fit fully within 10'. This would be a DM call, though arguably, in the normal context of English, a creature that has any part of it within 10' IS within 10'.


• This banishing effect of the bag of holding is not a spell. Only a feature that says it is a spell is a spell (as confirmed by Mr. Crawford here). So the Limited Magic Immunity to spells feature would not help.


• She is a minor deity. Again, whether this has any effect would be up to the DM, as there are no specific rules for a "creature type" of minor deity! If you are using an official set of stats from somewhere, then Tiamat (or her avatar) would be immune only if the stats say so. Otherwise, if home-brewed, it would be up to the DM.

Personally, assuming standard stats, I see no reason why this wouldn't work. The only caveat is that Tiamat is only stuck in the Nine Hells by divine purview (according to most backgrounds). If released then she would presumably be no more restricted than any other deity/avatar.

In other words - it might work. But there would be nothing stopped Her from returning from the Astral Plane looking for whoever did it. And She's gonna be ANGRY (-er)!

Yes, but They could not complete this using Mage Hand.
Mage hand has a 10lb limit, and a Bag of Holding weighs 15 pounds.