The Living Greyhawk Campaign Sourcebook (version 3.0, page 45) adds some clarifications and restrictions to the use of the polymorph (and related) spells/abilities in Living Greyhawk. This article further clarifies some of the information provided in the LGCS, specifically the issues of size change and equipment resizing. There are three keys to understanding size changes.
The first is clearly listed in the Player’s Handbook v.3.5 under a number of spells: “Multiple magic effects that increase size do not stack.” This means (among other things) that you can’t use a second casting of a spell (or make a second use of an effect) to further increase the size of a target already under the effects of the first casting of a spell. It also means you can not combine different spells that increase size to increase size twice. The way the second casting interacts with the first is not specified in the Player’s Handbook v.3.5, but it is specified in the LGCS: “If a spell increases your size and another spell tries to increase your size again, it fails (the rest of the spell works, it just does not change your size).” It’s important to note that the “rest of the spell works” means that the rest of the spell that was NOT tied to the size change works. We’ll explore that issue further, when we discuss individual spells/effects below.
The second key is to understand the way equipment resizing works in both D&D and Living Greyhawk. Some items are usable no matter the size of the user. This includes most potions, rods, scrolls, staves, and wands. Basically, any item that does not take a slot can be used no matter what size change is involved (although changing forms may not provide you with hands to wield an item, in which case they are either absorbed into the body or dropped). Weapons and shields also do not take a slot. However, as per the Dungeon Master’s Guide v.3.5, weapons and armor/shields do not resize by default (as they always come in specific sizes). So while the weapon/shield is usable after a size change, it is not resized for optimal use; most PCs suffer penalties for using incorrectly sized weapons as per the PHB (page 113) and an incorrectly sized shield is really only useful as a weapon. Since armor takes a slot and does not resize by default, a size change renders armor useless (as per the LGCS, it either falls off or is absorbed into the body).
This leaves items that take a slot (worn equipment), which is predominantly in the form of rings and wondrous items. As per the DMG (page 213), the core rules do not specify if magic clothing or jewelry (items that takes slots) resize automatically. It strongly recommends that they do so, but leaves the final call to the Dungeon Master. For Living Greyhawk, the circle members are the DMs for the campaign. For issues of campaign balance, among others, the circle has ruled (in the LGCS) that only cloaks and amulets/brooches resize automatically. All other items that take a slot do not resize automatically, and they either fall off or are absorbed into the body during a magical size change. A number of spells overrule the D&D and Living Greyhawk rules on equipment resizing, and these are detailed below.
The third key is to be sure to understand any restrictions built into an individual spell or effect. Some spells and effects limit the sizes available while others modify the equipment resizing rules. Some spells and effects have multiple parts to them, some of which are not tied to the size change.
Let’s look at a number of the spells or effects that involve size change. Unless noted otherwise, these spells and effects follow the default equipment resizing rules above, and the entirety of the effects of the spell or effect are tied to the size change, if a size change is involved.
Alter self: You must select a form within one size category of your normal form. Nearly all PCs are Medium or Small in their normal form, thus limiting them to Small through Large and Tiny through Medium, respectively.
Animal growth: Increases the size category of the animal by one. The spell also enlarges the equipment of the animal. All of the effects of this spell are tied to the size change except for the DR 10/magic and the +4 resistance bonus. A druid wild shaped into an animal can benefit from this spell only if the animal form it assumed via wild shape is the same size as (or smaller than) her normal form; otherwise the rule against stacking multiple magic effects that increase size applies.
Baleful polymorph: The spell always turns the target into a Small or smaller animal. As long as this is a size decrease, the rule about size changes stacking is not relevant here.
Enlarge person, mass enlarge person: Increases the size category of the humanoid by one. The spell also enlarges the equipment of the humanoid.
Giant vermin: Increases the size category of normal-sized vermin by an amount dependent on the caster level.
Polymorph: This spell allows you to assume a form as small as Fine or as large as one size category above the size of your normal form.
Polymorph any object: This spell forces the target into a form as small as Fine or as large as one size category above the size of its normal form.
Reduce animal: Decreases the size category of the animal by one. The spell also reduces the equipment of the animal.
Reduce person, mass reduce person: Decreases the size category of the humanoid by one. The spell also reduces the equipment of the humanoid.
Righteous might: Increases the size category of the caster by one. The spell also enlarges the equipment of the caster. All of the effects of this spell are tied to the size change except for the DR.
Shapechange: This spell allows you to assume a form as small as Fine or as large as Colossal.
Tree Shape: This spell transforms the caster into a Large tree or tree trunk. All equipment changes into the tree/tree trunk with the caster.
Wild Shape: This ability functions like polymorph with a few differences. The sizes permitted are determined by the level of the druid, not by the size of the druid’s normal form. Druids can assume sizes of Small and Medium at 5th level, Large at 8th level, Tiny at 11th level, and Huge at 15th level, restricted to animals initially, and then plants at 12th level. At 16th level, the druid can assume the form of a Small, Medium, or Large elemental, and, at 20th level, a Huge elemental.
Wild armor or shield special ability: Armor and shields with this special ability grant their armor/shield (and any enhancement) bonuses to their wild shaping users, even when the item is absorbed into the body during wild shape.
Some of these spells counter and dispel others, as noted in their spell descriptions. Others can be effectively used as a counter by changing someone back to their original size and form. Just keep in mind that while multiple magical effects that increase size cannot be stacked, it is possible to reduce the size of a target that has been enlarged in size and vice versa.