The Enlarge spell only affects one creature or object. What happens to a creature's armor or clothing if it grows?

Question

In AD&D 1e Player's Handbook, the Enlarge spell description specifically states:

It can be cast upon only a single creature or object.

It makes a differentiation between living and non-living matter:

The maximum volume of living material which can be initially affected is 10 cubic feet - for non-living matter, 5 cubic feet

Therefore, it's ambiguous as to what happens to a creature's clothing and armor (if it's wearing any) but it's implied that these don't grow which would imply the creature takes damage by instantly growing through a set of platemail, for instance. It is also not stated if the maximum space available is smaller than what size the creature or object will grow to. It is also left to the reader's imagination as to what happens if the reverse of the spell is cast and the creature shrinks and now is underneath a relatively heavy set of platemail, for instance.

Answer 1

PHB (1978): They increase along with their bearer

The spell explicitly says that it affects only a single creature or object, so a literal reading is that when cast on a character it would not increase their clothes, armor, items, etc.

However, this acts against the 'common wisdom' of spells in first edition. The spell invisibility, for example (PHB70) explicitly "causes the recipient to vanish from sight". Later, however, we read that "the allies of the spell recipient cannot see the invisible creature, or his, her or its gear..." It is implied that casting the spell on the creature includes in its effect everything carried.

Similarly, enlarge may be cast on a single object, but if cast on a single creature, it is implied that it increases all the gear the selected creature carries. If this were not so, other parts of the spell would not make sense, such as when it says:

a huge +1 sword is still only +1, a staff-sized wand is still only capable of its normal functions

If we obtained the huge +1 sword by casting enlarge on the sword itself, we would have no one to wield it and its damage would be moot. But by casting it on our fighter ally, we increase the +1 sword she carries by default, and thus we need to know that it is still just a +1 sword. Similarly for the wand - the spell description is implying that these items increased in size because they were borne by recipients of the spell.

The spell also says:

a giant-sized potion merely requires a greater fluid intake to make its magical effects operate...

This effect would not be achievable without a 'come along' principle. If I try to cast enlarge on a potion so that every member in my party can benefit from it, I can cast either on the potion itself or the container. If I cast on the container and the spell really affects only a single object, the bottle would grow but not the liquid within. If I cast it on the liquid but not the bottle, it would overflow or shatter its container. The note that one needs to drink more of a giant-sized potion makes sense only because we understand that casting enlarge on the container brings the potion along, and/or casting on our ally increases all the potion containers and potions that he is carrying as well - but that I still have the same number of potions as before in terms of their effect.

The PHB strongly implies that carried items increase along with their bearer or container.

DMG (1979): They either fall off or are destroyed

The DMG contains a section on "Spell Explanations / Spells: Special Commentary For Refereeing" (begins p.41). Some of the commentary therein is just advice for adjudicating spells. Some is "hidden rules" that players are not supposed to know (see, for example, fectin's answer here with regards to charm spells). But much of what is in the spell commentary section of the DMG serves to limit the power of spells from the PHB. As Gygax says at the outset,

There are, however, quite a number of special notes which you must be appraised of, as spells are often abused by players.

It is important to understand the context; that this is one of the purposes of this section of the DMG - 'here are some ways to limit spells that players abuse'. In the DMG, enlarge affects only the creature - its gear does not grow with it. And apparently, as OP asks, pre-DMG some people were doing damage or even killing opponents in armor by enlarging them and not their armor (and remember that this is a first level spell).

Thus, Gygax responds first by saying that you can't do that - that gear you grow out of drops off without damaging you. And second, if you are going to use the spell this way (targeting a creature in a way that might harm objects carried, like armor) then it is no longer a ranged spell (at 5' per caster level as printed in the PHB) but instead has become a touch spell (!). Even the ambiguous description in the PHB does not hint at this, so it appears that for this spell at least the purpose of the DMG listing is to limit its power in a way not present in the PHB.

All garments and equipment worn by a subject of this spell should be considered to automatically drop off if held by straps or fasteners, otherwise to split away during growth, so it is not possible to “squeeze someone to death in their armor” by means of an enlarge...Coats of mail, however, will be ruined if growth occurs while worn. Note that you can opt to make a target wearing objects an impossible task for an enlarge spell unless the character is actually touched so as to distinguish the creature from the objects.

The DMG asserts that if a creature is affected, their gear does not 'come along'. It either falls off or is destroyed as it is grown through, but this guidance is focused on preventing player abuse of the spell.

Answer 2

If you're reading implied damage into the normal use of a low-level spell that says nothing about dealing damage, you're misreading.

AD&D 1E wasn't super-careful about wording or interactions, relying on the DM to handle things sanely. If you try to read too closely into spell wordings like this, you end up interpreting Mirror Image as making naked copies of the caster because they don't mention duplicating gear in the images.

There're multiple possible readings that don't involve damage:

1. When they say, "It can be cast upon only a single creature or object", they just meant there is only one "direct" target; the creature is the only thing directly targeted, but it enlarges their gear as expected.

2. It can only be cast on naked creatures, or perhaps creatures clad solely in clothing that is less durable than their own bodies (which is destroyed as they grow). If rigid clothing/armor constricts growth, they don't grow.

As a DM, reading #1 is the only one I'd consider reasonable. I'd use ruling #2 for cases where the growth occurs in a constricted area (e.g. a narrow cave). It's clearly not restricted to one contiguous object (a chain can be affected, even though the individual links aren't even necessarily in physical contact with one another); I assume they were trying to make it clear you can't target multiple independent creatures or multiple independent objects, but generally, things that affect creatures implicitly affect their worn gear as well (and usually anything of reasonable size carried or held as well).

Answer 3

All garments and equipment worn by the recipient drop off without damaging the recipient, but possibly damaging the equipment.

Page 44 of the Dungeon Masters Guide (revised edition - December 1979) explains:

All garments and equipment worn by a subject of this spell should be considered to automatically drop off if held by straps or fasteners, otherwise to split away during growth, so it is not possible to “squeeze someone to death in their armor” by means of an enlarge. Material components possessed will not change size. Coats of mail, however, will be ruined if growth occurs while worn. Note that you can opt to make a target wearing objects an impossible task for an enlarge spell unless the character is actually touched so as to distinguish the creature from the objects.