Forcecage question

[lv99wizard]

Forcecage spell, p243 PHB:

An immobile, invisible, cube-shaped prison composed of
magical force springs into existence around an area you
choose within range. The prison can be a cage or a solid
box, as you choose.
A prison in the shape o f a cage can be up to 20 feet on
a side and is made from 1/2-inch diameter bars spaced
1/2 inch apart.
A prison in the shape o f a box can be up to 10 feet on
a side, creating a solid barrier that prevents any matter
from passing through it and blocking any spells cast into
or out from the area.
When you cast the spell, any creature that is
completely inside the cage's area is trapped. Creatures
only partially within the area, or those too large to fit
inside the area, are pushed away from the center o f the
area until they are completely outside the area.
A creature inside the cage can’t leave it by nonmagical
means. If the creature tries to use teleportation or
interplanar travel to leave the cage, it must first make a
Charisma saving throw. On a success, the creature can
use that magic to exit the cage. On a failure, the creature
can't exit the cage and wastes the use o f the spell or
effect. The cage also extends into the Ethereal Plane,
blocking ethereal travel.
This spell can’t be dispelled by dispel magic.


The spell says the dimensions of the cage are determined by the caster to a maximum of 20 feet for bars or 10 feet for solid walls. What happens if you polymorph an enemy into a tiny creature and cast forcecage onto it with dimensions of 1 foot per side and then drop polymorph the following turn? The spell takes effect since the creature is fully enclosed at casting. Lets say the creature's size-class is Large and the forcecage is the barred variant. What happens when it reverts to normal size?

[JackPhoenix]

The creature appears in the nearest space big enough to accomodate it and takes some force damage... let's say 10d10.

[lv99wizard]

How did you arrive at that number? Do you think it should scale with the creature's original size-class rather than be flat 10d10?

[JackPhoenix]

How did you arrive at that number? Do you think it should scale with the creature's original size-class rather than be flat 10d10?

Pulled it out of my... ahem.

No, actually, I've looked into DMG for improvising damage, 10d10 is the figure given for being "crushed by compacting walls", which seems fitting. Page 249, in case you're wondering.

Also, it's just 1d10 lower than the figure for the damage single-target level 7 spell should do, so that felt like a nice coincidence.

My first idea was to make it just 1d10, like ghost takes if it gets stuck inside a solid object at the end of its turn, but then I decided to look deeper. That's the reason, however, why the damage type used is force.

[BurgerBeast]

TL;DR JackPheonix's answer is great.

This situation has no rules, so is the DM's call.

I can imagine some DMs saying the creature is pushed out of the cage and unharmed, perhaps pointing to the conditions given in the spell as evidence that the spell is meant to trap enemies but not damage them. I can imagine some other DMs ruling it an auto-kill, and using the resource expenditure and/or the "common sense" of the situation as justification. And obviously those are the extremes. There could be anything in between.

I think JackPheonix's answer is a great answer.

[Blacky the Blackball]

This is a specific question, but it's actually just one case of a general question:

What happens when (a) magic affecting something, or (b) magic ceasing to affect something, causes that thing to grow to a size that won't fit in its current location?

This happens in the forcecage example you use, but can also happen with things like polymorph being cast on a creature to turn it into something big while it is in a small space, or a wild-shaped druid being trapped (or even knocked unconscious) while in a small animal form, or when a polymorphed or wild-shaped creature is eaten by something.

There's no official rule for this, so you can either try to come up with a different house-rule (or on-the-fly ruling) for each situation or you can come up with a single house rule for the general case.

In my group, we've done the latter. After discussion, we decided that we liked the common fantasy trope of the person being reduced/polymorphed and trapped in a jar on the villain's desk, and we didn't like the idea of being able to feed a creature something that is enchanted to be small and then cancelling the enchantment to make the creature explode or the case where someone is reduced and placed in a small cage for them to then take huge amounts of damage when the magic wears off. They felt like "exploits" to us.

So the house rule that my group uses is:

If a magical effect would increase the size of a thing to the point where it will no longer fit in its current location, the magical effect fails. If the ending of a magical effect would increase the size of a thing to the point where it will no longer fit in its current location, that effect will be artificially extended and will not end until the aforementioned situation is no longer the case.

We're not pedantic about the definition of "will no longer fit", in that we allow it to displace water or push apart curtains, or lift something light; but we draw the line where a solid object (possibly the one changing size, possibly the thing blocking the size change) would have to be damaged or broken for the size change to happen.

[ShikomeKidoMi]

TL;DR JackPheonix's answer is great.This situation has no rules, so is the DM's call.I can imagine some DMs saying the creature is pushed out of the cage and unharmed, perhaps pointing to the conditions given in the spell as evidence that the spell is meant to trap enemies but not damage them. I can imagine some other DMs ruling it an auto-kill, and using the resource expenditure and/or the "common sense" of the situation as justification. And obviously those are the extremes. There could be anything in between.I think JackPheonix's answer is a great answer.

Yeah, I probably would have gone with the pushed out of the cage and unharmed effect myself, as it seems to fit with the way spells usually deal with the 'placing a creature inside an object' effect. See spells such as Maze, where a creature that would be returned inside an object appears inside the next unoccupied square with no damage, but JackPhoenix's answer is perfectly logical.

[Vogonjeltz]

Pulled it out of my... ahem.

No, actually, I've looked into DMG for improvising damage, 10d10 is the figure given for being "crushed by compacting walls", which seems fitting. Page 249, in case you're wondering.

Also, it's just 1d10 lower than the figure for the damage single-target level 7 spell should do, so that felt like a nice coincidence.

My first idea was to make it just 1d10, like ghost takes if it gets stuck inside a solid object at the end of its turn, but then I decided to look deeper. That's the reason, however, why the damage type used is force.

Forcecage already states that a creature which doesn't fit is displaced into the nearest spot at no damage. Seems like the same thing is appropos. It's the same effect as with Teleportation Circle.


This situation has no rules, so is the DM's call.

No rules...Except for the rule in the spell.

[Aett_Thorn]

Forcecage already states that a creature which doesn't fit is displaced into the nearest spot at no damage. Seems like the same thing is appropos. It's the same effect as with Teleportation Circle.



No rules...Except for the rule in the spell.

Except that the text that you're pulling that from is about only when the spell is cast:

"When you cast the spell, any creature that is completely inside the cage's area is trapped. Creatures only partially within the area, or those too large to fit
inside the area, are pushed away from the center of the area until they are completely outside the area."

It says nothing about what happens if a creature that is already trapped by Forcecage grows too large while inside of it. As such, the DM can make a ruling as to what happens.

[Beelzebubba]

Except that the text that you're pulling that from is about only when the spell is cast.

It says nothing about what happens if a creature that is already trapped by Forcecage grows too large while inside of it.

So?

This isn't 3E. They didn't spend exhaustive amounts of work to lay out every single thing, but if you look at how the rules work, they definitely say what happens in similar situations. Look at Meld into Stone, for example.

There is an ethos at play here. The game explicitly nerfs low level spell combos that are as effective higher level spells when strictly hewing to 'logic'. It cares less about physics and more about what makes for a balanced game. It also gets rid of horribly gory death.

So, no, it's not really 'the game says NOTHING so the ref can do ANYTHING'. It just doesn't lead you by the nose at every step of the way.

If you want to think that way, sure, go for it. You can also kick your dog all you want, we can't stop you. :smallsmile:

[Aett_Thorn]

So?

This isn't 3E. They didn't spend exhaustive amounts of work to lay out every single thing, but if you look at how the rules work, they definitely say what happens in similar situations. Look at Meld into Stone, for example.

There is an ethos at play here. The game explicitly nerfs low level spell combos that are as effective higher level spells when strictly hewing to 'logic'. It cares less about physics and more about what makes for a balanced game. It also gets rid of horribly gory death.

So, no, it's not really 'the game says NOTHING so the ref can do ANYTHING'. It just doesn't lead you by the nose at every step of the way.

If you want to think that way, sure, go for it. You can also kick your dog all you want, we can't stop you. :smallsmile:

Sure, this is an overall ethos at play here, and I am willing to bet that MOST DMs would follow it. But that doesn't mean that they necessarily need to. This is a spot where various rules COULD come into play, but the spell itself doesn't say what would happen in these cases. As such, the DM would need to make the ruling. There is literally no RAW in this case.

[RSP]

Forcecage already states that a creature which doesn't fit is displaced into the nearest spot at no damage. Seems like the same thing is appropos. It's the same effect as with Teleportation Circle.



No rules...Except for the rule in the spell.


So?

This isn't 3E. They didn't spend exhaustive amounts of work to lay out every single thing, but if you look at how the rules work, they definitely say what happens in similar situations. Look at Meld into Stone, for example.

There is an ethos at play here. The game explicitly nerfs low level spell combos that are as effective higher level spells when strictly hewing to 'logic'. It cares less about physics and more about what makes for a balanced game. It also gets rid of horribly gory death.

So, no, it's not really 'the game says NOTHING so the ref can do ANYTHING'. It just doesn't lead you by the nose at every step of the way.

If you want to think that way, sure, go for it. You can also kick your dog all you want, we can't stop you. :smallsmile:

So in your games the way to easily escape forcecage is to cast Enlarge? A second level spell that would make you larger than the cage nullifies a 7th level spell that is otherwise almost inescapable?

Likewise Wild Shape or Polymorph would get you right out as well.

I'd not go with this ruling

[Easy_Lee]

Let's consider another situation. The players polymorph a large creature, then place it in a small enclosed space and release the spell. By RAW, there are no general shunting rules of which I am aware, but we do have specific shunting rules for spells like etherealness.

I think most DMs would rule that the target takes damage if the players do the above. So, I find it peculiar that some don't think force cage should deal damage when basically the same thing happens.

As simple reason why the force cage would damage creatures that grow inside of it, but not damage anything when it's cast: it has to push air out of the way to come into existence. It ought push anything else in the way as well.

[RSP]

I usually go with this rule from Enlarge/Reduce:

"If there isn't enough room for the target to double its size, the creature or object attains the maximum possible size in the space available."

Combined with the rules for squeezing to fit in an area smaller than your size category.

In the case of the little Forcecage, I would just have the creature maintain little size until the Forcecage expires.

[ShikomeKidoMi]

So in your games the way to easily escape forcecage is to cast Enlarge? A second level spell that would make you larger than the cage nullifies a 7th level spell that is otherwise almost inescapable? Likewise Wild Shape or Polymorph would get you right out as well. I'd not go with this ruling

Enlarge specifically says it won't cause you to grow more than the largest you can reach before hitting any impediment (such as a Force Cage) in the way.

Wildshape or Polymorph might be issues though.