Let's be very specific. Assume you have two casters. The first one casts polymorph on, lets say, a Kraken, and uses portent to assure a failed save. He turns the Kraken it into a regular 1/2 inch diameter spider. The second caster casts wall of force and creates a no save 1/2 inch diameter sphere of force around the spider-kraken. The first caster immediately stops concentrating.

What happens?

For reference, the average 5e Kraken is about 100 feet in length and weighs about 4,000 pounds.

What happens if you very soon afterwards stop concentrating on the wall of force as well?

This is not the same as "running out of wildshape" because wildshape has very different language, and is generally not dismissable by an enemy (it doesnt go away as a result of anything other than damage). It would be completely within the boundaries of the game for the DM to say to a druid, "no you cannot choose to end your cat wildshape while you are still within the iron pipe."

And, unlike wildshape, which takes a full action to drop (thus likely occurs slowly), the physics answer would be very different (sudden burst of pressure as opposed to slowly building pressure).

Forcecage is also not applicable as a point of comparison as it has specific language regarding not being able to fit.

Also, for the record, this comes up all time because we have a caster with a Ring of Spell Storing, polymorph and wall of force.

  • 4
    \$\begingroup\$ Ending the question at What happens? is the best bet here to stave off potential closure. RPGs are better story engines than physics engines. (Also see this Meta question.) Further, is this idle curiosity, or is this an actual problem that's occurred (or will occur) in a game you're in? \$\endgroup\$ Feb 2, 2018 at 6:57
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    \$\begingroup\$ A constant with RPGs is that if something seems even remotely possible, regardless how absurd it is, one player will attempt to do it. The "Enlarge Creature" spell already has a stipulation in it to prevent a similar situation, but this is "Polymorph", or rather the ending of said spell. \$\endgroup\$
    – Anonymous
    Feb 2, 2018 at 8:36
  • \$\begingroup\$ @Anonymous Someone may attempt it doesn't make every question suitable for the site, though. The site's supposed to deal with real problems that, ideally, answers can solve or with potential problems for future-proofing. Just wondering because somebody somewhere might do it is too low a bar. Were the question ended with I have two casters in my game who plan to team up to incarcerate and detonate enemy creatures in the fashion this question describes. How should I handle it? then I'd've not offered any commentary. ;-) \$\endgroup\$ Feb 2, 2018 at 9:01
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    \$\begingroup\$ Related: Can I squish people with a wall of force? \$\endgroup\$
    – mattdm
    Feb 2, 2018 at 11:11

1 Answer 1


I have had a very similar situation come up, but with a small hole in the ground instead of a wall of force. A character polymorphed some nasty monster into a snail, dropped the snail in a small hole, then plugged the hole with rock.

The GM ruled that the conversion back to the non-polymorphed form was put on hold until there was room to safely transform.

All of us at the table agreed with the ruling, for two reasons. First, the DM didn't want polymorph to become a 'save or die" spell. Second, he said if he allowed us to do it then he was absolutely going to use it to kill characters, and were we OK with that.

We discussed this for a few minutes and all agreed to file it under, "cool use of a spell" but not run it that way.

To give some official weight to this ruling, at DNDBeyond the spell is not tagged DAMAGE, unlike actual save-or-die spells like disintegrate and power word kill.


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