For context, my party is going to face a Gargantuan (20 by 20 ft. or larger) creature with obscene levels of health.

The polymorph spell description says, in part:

This spell transforms a creature that you can see within range into a new form. An unwilling creature must make a Wisdom saving throw to avoid the effect. The spell has no effect on a shapechanger or a creature with 0 hit points.

The transformation lasts for the duration, or until the target drops to 0 hit points or dies. The new form can be any beast whose challenge rating is equal to or less than the target’s (or the target’s level, if it doesn’t have a challenge rating). [...]

Would it be possible to cast the demiplane spell, polymorph the Gargantuan creature down to size, and then shove it into the demiplane, trapping it there?

After trapping it there, would it be possible to release it in, let's say, Hell or just a 'void'?

This assumes that the creature has already used up everything it can to resist magic. The creature is being shoved into the demiplane.


1 Answer 1


Trap yes, safely release into the wild, not so much

The key here, is the nature of the demiplane spell. It creates a door to a demiplane and the door is sized for medium creatures. Thus a creature polymorphed into a medium sized creature can be dragged, shoved, pushed, or launched through exactly the same as it can through any other door.

However, the demiplane does not collapse at the end of the spell's duration. The plane just stays (make sure not to trap yourself) and can be reconnected to later. The only way to connect the demiplane to another plane (say the Nine Hells) would be to travel there yourself, or have another caster with familiarity to the demiplane, and cast it from that plane.

The other demiplanar options aren't much help either: maze, imprisonment, and mordenkainen's magnificent mansion all return the creature to the space it left and banishment and banishing smite do they same unless it's native to a different plane, in which case it goes there.

There are two spells which let you throw a creature into the Abyss (or other plane of your desire): gate or plane shift. Gate creates a portal which teleports the creature directly (demiplane needed) and the portal can be up to 20 ft in diameter, so no polymorph is need either (although it may help with the whole pushing aspect). Simply close the gate behind the creature by ending your concentration once it is through. Plane shift (in its third mode) is more direct, allowing you to make a spell attack and if the creatures fails a Charisma throw, it is teleported to your desired plane. You will need a tuning fork for the particular plane, so some preparation is required.

  • 2
    \$\begingroup\$ side note: Gate can be used to push a creature through, and Plane Shift can also be used to teleport another creature to a random location on a specified plane of existence. \$\endgroup\$ Commented May 31, 2020 at 14:04
  • \$\begingroup\$ @PixelMaster Gate is a really good shout actually (as it accomplishes what is attempted), I keep forgetting about that spell's normal mode, but plane shift has the "you and [a] willing creature" part which makes it 1. probably not work and 2. not be a good time for you if it did. \$\endgroup\$
    – Someone_Evil
    Commented May 31, 2020 at 14:12
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    \$\begingroup\$ @Someone_Evil Plane Shift also has the "You can use this spell to banish an unwilling creature to another plane" part. \$\endgroup\$ Commented May 31, 2020 at 17:33
  • \$\begingroup\$ @Pleasestopbeingevil Apparently I'm bad at reading the entirety of spells today, thank you for correcting me one that. \$\endgroup\$
    – Someone_Evil
    Commented May 31, 2020 at 18:00

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