I was thinking recently about the rules governing spells that change a character's size, shape, and ability to merge with other material, primarily in regard to how they affect a character's possessions and equipment. Rather than starting a discussion from scratch, I searched the forums for any previous topics that might have covered these scenarios.
I found
this topic that talked about the relationship between size and mass, originally about an errata in Combat Companion, but later about how it might relate to other publications.
I found
this topic that talked about personal equipment and familiars and auras, and primarily how they are affected by shapechanging and teleportation.
I found
this topic that talked about playing a giant character and the considerations of sustenance and just interacting in a non-giant world.
None of these seemed to directly address the questions I had in mind (and I had no interest in necroposting on topics from 10-15 years ago), so here we are.
To start with, I scoured the RM2 books for spells that deal with these changes. I found about a dozen spells that simply increase or decrease the caster's size, about 20 spells that allow merging with or passing through materials, and over 100 spells that change the caster into some other form, either with or without the abilities of that other form.
For the size change spells, they all use Shrink Self and Enlarge Self from the Closed Essence Living Change list as a guide. This means that the change is listed as a difference in mass, but "height in most situations." The changes vary as either +/-50% or +/-10%/level, depending on the strength of the spell, with usually a floor of 90% reduction ("usually" because the Dervish base Changing Dances list doesn't specify). No mention is made in any spell description of what happens with personal items or equipment.
For the shape change spells, the vast majority of spells list the change as a difference in mass, anywhere from 1/2-2x to 1/40-400x ("vast majority" because the Ranger base Nature's Guises list says a change in "size", but that seems to be an outlier). The larger range (1/40-400x) spells are the Arcane Shapechanging Ways and Druid base Nature's Forms lists from RMC1, and various Doppelganger lists in RMC7. (For this category, I also include Waterform, Mistform, Mote Form, and Flattening spells.) No mention is made in any spell description of what happens with personal items or equipment.
For the merging spells, the only mention of personal items is a tangential one coming from the 50th level Mystic Hiding True spell, which is a combination of Merge, Unpresence, and Nondetect (which covers objects on the caster's person).
As my findings relate to the previous-linked discussion on size vs. mass (including the excellent tables on page two of that topic), I would posit that the intent of the original definitions of the Size Change spells really did mean "height" and were meant to achieve a greater potential amount of volumetric change because they only involved the existing body of the caster (hence why they were listed as "height in most/normal situations", which could result in much more than an equivalent change in mass because 2x height = 8x mass while 2x mass = 1.26x height). The spells with the greatest amount of change (10%/level) are only tenth level (Closed Essence Enlarge and Dervish base Growing Whirl).
On the other hand, I believe the Shape Change spells really did mean "mass" and would necessarily be limited to a smaller change in size for the lower spells because of the extra magic required to change the form of the caster. So the spells that go up to a 400x change in mass (not 400%, mind you, which is only 4x) would include whales and dragons and are anywhere from 20th-50th level (Arcane Shapechanging Ways and Druid Nature's Forms). This is further reinforced by the description of Druid Beast Change True mentioning dragon breath as a special ability.
As to the second linked topic about auras, the only mention I could find in RM1/2 that seemed relevant was in the "Assumptions and Special Notes" sections of the 1981 and 1984 editions of Spell Law. There it mentions:
"20) Unless otherwise specified, a spell which affects the target also affects the object he carries. An exception may be made for certain unusual items. When computing the effects of an Elemental Attack Spell, however, always make a distinction between the target and the items he bears; simply follow the appropriate results on the tables."Curiously, while several of the other notes in this section were rolled into the 1989 edition of Spell Law (red band), the content of this note was not. And, while RMSS and RMFRP Spell Law did have a section on "Changing Spells," this only was to clarify the physical or special abilities that the caster did or did not receive of the new form, and made no mention of items or equipment. The most helpful bit in later editions is found in RMC Spell Law. Though it technically wouldn't necessarily apply to RM2, it does make sense of it a bit better:
"Each living or animate thing is surrounded by an aura, their personal field of essence, which casters manipulate to create effects. This field also enables beings to resist effects. [...] This aura is also why casters can use attack spells on beings, but cannot attack with utility spells, and why your personal gear resists with you, rather than being separately attacked by all effects. Since your clothing and gear is inside or in contact with your personal aura, it receives a certain amount of shelter from effects. This aura also explains why "1 target" effects like a teleportation will grab the target, and all of their clothing and equipment, rather than whisking them off naked."Now, putting these things together, it seems reasonable that normal items and equipment would be incorporated into the effects of these spells. Thus, all of your stuff would merge into a stone wall with you, or grow or shrink in proportion to the rest of your body, possibly resulting in a 4-foot-long short sword(?!). I'd guess the "unusual" items might be intelligent or especially powerful, such as artifacts or potent items, but would that also include intermediate things like mithril chain mail? It'd be kind of awkward to attempt one of those spells and either be blocked from merging or having your body be distorted around things that don't move with you.
Am I way off with any of my thinking here, or have I overlooked any points?
