If I place a Bag of Holding inside another Bag of Holding, can I use Misty Step to get away before the gate to the Astral Plane opens?

Question

Placing a bag of holding inside another bag of holding opens a gate to the Astral Plane, as discussed here: Is it possible to stuff a Bag of Holding inside another Bag of Holding?

Can I use misty step to get away before the gate has opened? For example, a character runs toward a monster, puts one bag of holding inside another bag of holding, and uses misty step to avoid being sucked through this gate. Does this work?

Here we assume that a bag of holding is a “similar item” that creates an extradimensional space, per its description (as suggested in the answer above).

Answer 1

The effect happens instantly upon one bag entering the opening of the other (see other answers for details of that reasoning).

If you want to Misty Step away, you need to create some kind of time delay. e.g. place one bag on the ground and drop the other bag from waist height as you Step.

Presumably a DM would get you to roll something to get the timing right and not miss. A DM might also require you to spend your Action fiddling with 2 bags, and give an aware enemy a chance to kick away one bag on the ground. (See discussion in comments).

Note that any spell with a 1 Action cast time can be Readied, holding on to the energy to release at a chosen moment (as a Reaction), so you could do this with spells like Dimension Door or Teleport (like Misty Step both have only verbal components so you could have bags in both hands while casting). But not Misty Step itself because its cast time is 1 Bonus Action.

Readying a spell has the advantage that you know you're safe from Counterspell; the window of opportunity was during the Action to cast, not while releasing the energy. Having Misty Step counterspelled after you drop the bag could really spoil your day. RAW, doing it this way to make the timing easier and safer might cost you your reaction (reacting to the bag starting to fall).

You could also use Mage Hand or Telekinesis to drop one bag into another after throwing an open bag out near the bad guy, have a familiar do it, or any number of other ways to avoid needing to bamf away yourself.

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Or build a projectile with two bags, with the back one attached to a weight, and the front one held open. So when it hits something, the weight forces the back bag through the opening of the front bag. Similar to a nuclear bomb mechanism that brings together two pieces fissile material. (This idea has been suggested and discussed before).

If you didn't prep such a mechanism ahead of time, using gravity for a "fuse" should work.

Answer 2

Per the description of Bag of Holding:

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.

Placing a bag in a bag starts an instantaneous reaction. The keyword "and" means there is no difference between the destruction and the opening to the Astral Plane. Otherwise there would be explanation of some sort of countdown.

Answer 3

The description, as mentioned on the question you linked, says the gate opens "instantly", so I'd say no: as soon as the slightest part of a bag goes inside another, the gate is open.

Answer 4

I'd very much put this conundrum into the 'Should bring disaster of one sort or another onto the character' category.

You mention whether you can cast the spell 'before' the effect, depends on whether there's a somantic component to the spell I suppose, you can't start to cast the spell, then get your bags ready, then finish the spell, then... but I suppose you could use a foot to drop one into the other...

In terms of game mechanics, obviously the timing of the spell would affect where the character was when one bag went into another (whether the whole bag or just the first thread of it needs to go in the produce the effect), ultimately the destruction/gate effect either happens before or after the spell activates, at a nano-scale of timing so either the character is still where the bags are if they do it by hand, or if they use some kind of gravity/delay mechanism to have one fall into another then sure, they're wherever they are and the bags are... well, no longer wherever they were when it happens. Same as if they cast the spell and a nearby character puts the bag into the other bag before or after the spell activates - when you get to a sufficient level of time slicing, nothing is simultaneous.

Either way, Misty Step is short range, quite possibly less than the reach/size/spell/psionic range/maw size of something horrific that I'd be pretty sure to decide emerges from the gate to see what all the commotion is.

Opening a random gate to the Astral plane by such shenanigans would invariably be a bad thing in my campaign... it doesn't mean you can step through it or benefit from it in any way, it's an Astral gate, it's not under your control and doesn't want to be your friend.

And where are all these bags of holding coming from ?? - seems such a waste.

Call me a purist but this kind of thing smacks of trying to exploit wording in texts that the characters themselves don't have access to - there aren't game rule books in the D&D universe, just in the real world and in the end, the DM decides how they want to interpret the rules. I'd suggest just fighting the monster and using the 2 bags of holding to carry its loot away.

There's more pleasure to be had in playing the game than playing the rules so as a DM I discourage this sort of play.