Pinned / tied creature polymorphs into larger creature: how do you rule it?

[Astral Wanderer]

If a creature is being kept pinned in a grapple, or tied with ropes or chains, and uses a change shape ability or a spell or spell-like ability to polymorph into something larger, how would you rule it?

The Polymorph subschool description in the CRB doesn't mention anything about that.

Unless there are some other relevant rules somewhere, I'd say the ability/spell simply fails; lacking necessary free space, the effect is cancelled to prevent the creature from suffering damage from whatever is squeezing it. In case the creature was going to turn smaller, it'd work because there is no intrinsic potential harm in doing so.

There's plenty of threads about the other case, the creature getting smaller, but I couldn't find any about larger.
Some argued about the ropes or chain being considered the creature's gear because they're being worn, but like others in those same threads pointed out, it's quite a huge stretch and it would lead to all kinds of issues.
In the case of being grappled, someone noted there's no rule about size change breaking a grapple, and by extension a pin, and I'd couple that with the effect just failing as mentioned above.

Does anyone remember some other rule that would be relevant?

[Diego Rossi]

As the size requirement for grappling was removed years ago, a grapple target becoming larger shouldn't break a grapple, but it makes way harder to maintain it.

With rope or chains, if the pinned/grappled creatures try to become larger I would have them make a check to burst the restains, using the new size and strength. If the check succeeds, the shape change succeeds, if it fails, the shape change is canceled before it damages the used (and the daily use/charge/spell is used up).

Note that not all shape changes will have problems. If a manacled human turns into an octopus, even a large one, the manacles will simply slide off. An octopus has no wirsts and hands.

[Gilfalas]

Astral Wanderer wrote:

If a creature is being kept pinned in a grapple, or tied with ropes or chains, and uses a change shape ability or a spell or spell-like ability to polymorph into something larger, how would you rule it?

The Polymorph subschool description in the CRB doesn't mention anything about that.

Unless there are some other relevant rules somewhere, I'd say the ability/spell simply fails; lacking necessary free space, the effect is cancelled to prevent the creature from suffering damage from whatever is squeezing it. In case the creature was going to turn smaller, it'd work because there is no intrinsic potential harm in doing so.

There's plenty of threads about the other case, the creature getting smaller, but I couldn't find any about larger.
Some argued about the ropes or chain being considered the creature's gear because they're being worn, but like others in those same threads pointed out, it's quite a huge stretch and it would lead to all kinds of issues.
In the case of being grappled, someone noted there's no rule about size change breaking a grapple, and by extension a pin, and I'd couple that with the effect just failing as mentioned above.

Does anyone remember some other rule that would be relevant?

In our games we treat non magical restraints the exact same as anything else worn by the creature shapechanging. If there clothing or gear can be subsumed into their new form then so can the restraints.

Magical restraints we treat as immutable and can block the change based on the spell save or item level but those are obviously home rules.

[Diego Rossi]

Quote:

When you cast a polymorph spell that changes you into a creature of the animal, dragon, elemental, magical beast, plant, or vermin type, all of your gear melds into your body.

...
If your new form does not cause your equipment to meld into your form, the equipment resizes to match your new size.

RAW, you don't get to choose what changes. All your "gear" is affected. Included magic equipment.

Nowhere in the rules is defined what is your "gear".

I consider something gear everything that fulfills the following requirements:
- whatever you can transport within the limit of your normal encumbrance (i.e., up to your heavy load);
- is not affixed to an unmovable object;
- if you stow it away it will not stick out of your square (weapons are an exception, long spears and co. transform with you);

So, a rope binding you will be gear and transform. After the transformation, it will not limit your movement, but it will return to do so when the transformation ends.
A chain linked to a wall will not transform.

Pretty weird, but it is magic.

[Azothath]

Astral Wanderer wrote:

If a creature is being kept pinned in a grapple, or tied with ropes or chains, and uses a change shape ability or a spell or spell-like ability to polymorph into something larger, how would you rule it? ...

GM Rulings just don't pop out in a vacuum. okay, sometime they seem to - lol - but those are not thoughtful or "good" examples

there are several hurdles in the sequence of events leading up to the polymorph(Ex or Su). I don't think ignoring them is a good idea as we have a caster in a melee situation.
RAW wise the polymorph:T5 spell or wildshape(Su){references various spells} does not mention affecting a condition like bound, helpless, grappled, pinned, or any melee state. So we assume it doesn't as spells only do what they say they do. It may grant size, ability score bonuses or circumstance bonuses on the following actions but the caster just spent their standard casting a spell (and there are serious melee consequences during that casting action).
There is also the giant nerf-bat that PF1 took to polymorphs, the caster does not change type only their look. Thus a humanoid (elf) caster in spoogebob bloomers can transform into a centaur in the same large sized bloomers and still be subject to extra damage from a bane humanoid(elf) weapon. Why not bindings or being touched/pinned?
Polymorphs/Wildshape don't move the target creature from their square so at least part of them still fills their original square and is adjacent to a foe.
So the simple close to RAW ruling is it does nothing in the moment. Doesn't affect conditions, states of melee, or other things the spell/ability doesn't address.