Save DCs
The fact that the base 3.5 system bases spell DCs on spell level is a substantial flaw for a number of reasons. First of all, from 0-level to 9th level spells, this produces a 9-point save DC disparity, which is very much unacceptable if you want people to either care about 0 level spells or not get massacred by 9th level ones. Secondly, this makes saves extremely difficult to balance, as they would quickly end up being either too good or too weak if this system is maintained. Lastly, this doubly screws casters which don't get access to 9th level spells at all, such as paladins and rangers, which isn't what we want at all.
Save DCs for all spells are now calculated as follows: 10 + 1/2 the caster's character level + the caster's relevant ability modifier.
Caster Level
Making caster level independent of character level is also very problematic. It makes casters who multiclass have to burn feats to not constantly lose to SR, makes partial casting in anything a problem to give out, and generally is subject to too many additional modifications all over the place through items, other spells and so on. It needs to be put back on secure and sensible pegs, and we're going to do just that.
A character that can cast spells of any sort, no matter the source, always has a caster level equal to their character level. Always, forever and eternally. Nothing can increase or decrease this for any reason whatsoever, whether by item, spell, ability, or anything else.
Spell Resistance
Since the SRD is actively contradictory on this, and that voluntary save failure is already in the system, there's no reason to make spell resistance as clunky as it currently is.
A character may elect to have their spell resistance fail automatically against any spell targeting them if they wish. This requires no action.
New Action Types
The addition of the swift and immediate action was one of the best things done in 3.5 over 3.0. However, especially where immediate actions are concerned, some timing restrictions were never put in place, leading to some confusion about whether these actions could be used before the ability they are 'responded to' with, or after. This is relatively simple to fix as well.
Immediate actions are now divided into two forms: immediate reactions and immediate triggers. Both function according to the rules regarding immediate actions, except for one difference. Immediate reactions take place before the action that they were declared 'in response' to, while immediate triggers take place after the action instead.
New Magic Types
Not so much a fix as a clarification of an element of the Tome of Prowess, this creates an additional magic type on top of the original two of arcane and divine: natural magic.
There are now three forms of magic. Arcane magic comes from the imposition of a character's will onto their environment, divine magic is granted to a character from some higher power, such as an outsider or a deity, while natural magic is granted by a close connection to some manner of environment or plane in general. Bards, wizards and sorcerers wield arcane magic, clerics wield divine magic, and druids wield natural magic.
Schools of Magic Redefined
The schools of magic have traditionally had extremely poor definitions, with significant overlap, and some schools gaining far more than they should, while others gaining much less so. In order to try and bring some sense of order to the schools of magic, they are being rearranged and redefined as follows. Additionally, due to the expansion of their definitions, their wording needed to be changed.
Abjuration
Abilities from this school affect other abilities. These abilities are usually defensive in nature, but also often interfere with the workings of other abilities, or cause them to function in ways they normally wouldn't. Most protective abilities are abjurations.
If an abjuration ability creates a barrier that keeps out certain creatures or objects, this barrier cannot be pushed aggressively against such creatures or objects. If this is done, the user will feel a pressure against the barrier, and repeated attempts will cause the ability to fail.
Conjuration
Conjuration abilities create matter in all forms. [Summoning] and [Calling] abilities are nearly always conjurations, as well as any abilities that create objects out of thin air. Creatures that you conjure usually, but not always, obey your commands. Conjuration cannot manipulate matter (like transmutation), nor does it create or manipulate energy (like evocation).
A creature or object created by a conjuration ability cannot appear inside another creature, but an object that has at least one open side and that can fit the creature or object being created can accomodate them normally. The object or creature must appear within the range of the ability, but does not have to remain that way.
Divination
Divination abilities give access to information or sensory input that would not otherwise be available to the user. All abilities that involve perceiving anything that wouldn't normally be visible, audible etc., predicting things to come, or viewing remote locations are divinations.
A divination with a cone-shaped area extends from its user the given distance, and can move with them. It extends in the direction that the user looks, and the cone defines the area that the user can sweep or cover each round.
Enchantment
Enchantment abilities affect, control or alter the minds of other beings. Abilities that induce fear, emotion or similar things, as well as anything that affects memory, are enchantments. Most enchantments have the [Mind-Affecting] tag.
Evocation
Evocation abilities create, control and alter energy. Abilities with the [Teleport] tag or that involve planar travel, as well as anything that controls gravity, fire or a similar energy, are all evocations. Evocations tend toward big, explosive effects. Evocation cannot create or manipulate matter (that's what conjuration and transmutation are for, respectively).
Illusion
Illusion abilities affect, control or alter the senses of other beings, as well as magical or supernatural 'senses'. Abilities which create images of things that are not real, alter appearances and dull or remove certain senses are all illusions. Illusion cannot give access to genuine information, and also cannot be used to give senses (as both of those are divination's job).
Necromancy
Necromancy abilities manipulate life and death. Abilities that deal with negative and positive energy, healing, souls and the undead are all part of the school of necromancy.
Transmutation
Transmutation abilities alter and manipulate matter. Transmutation cannot create matter (that's conjuration's job) and it can't create or alter energy (that's evocation).
A Note on Subschools
As you might have noticed, subschools are gone. These have been turned into tags, which are described below in more detail.
Tags
While the descriptors used by 3.5 are a good classification tool, they ultimately don't go far enough. As a result, to replace descriptors and subschools both, a system of tags is being introduced. These determine how the abilities tagged with them interact with other abilities, as well as some additional rules, which will be described here.
Tag Groups
These are similar groups of tags that are listed near each other for ease of reference and to avoid repetition.
Companion
These tags indicate that these abilities bring creatures across large distances to serve the users of the ability.
Notated As: [Calling]
Game Rules: Creatures brought by these abilities are fully real, and can enter antimagic fields without harm. Bringing a creature with an elemental subtype using such an ability gives that ability the appropriate [Elemental] tag as well.
Notated As: [Summoning]
Game Rules: Creatures brought by these abilities are only replicas. They can be 'dispelled' as if they were an area spell, and entering an 'antimagic field' causes them to wink out of existence. Such creatures are non-specific and untrainable, and cannot be brought into an environment that cannot support them. These creatures cannot use any abilities that summon or create creatures, nor can they use any [Teleportation] abilities or abilities that allow them to travel between planes. Bringing a creature with an elemental subtype using such an ability gives that ability the appropriate [Elemental] tag as well.
Deception
These tags indicate that these abilities alter the senses of their targets, making them perceive something that isn't there.
Disbelief
Creatures that encounter either an [Image] or [Phantasm] ability do not usually get a save to recognise it as not real. They do, however, receive a save (usually a Will save, marked as a "disbelief" save) if they carefully study or interact with the illusory perception in some way. Only if this yields a response that is atypical or strange will such a save be permitted. "Studying carefully" requires a lot of scrutiny, and this means that a casual glance, a few seconds of listening or something similar are not enough; thorough searching and probing, detailed listening for at least ten seconds and something of that degree are required to gain a save.
Additionally, most individuals don't expect their senses to lead them wrongly, and quite frequently, a wall made of fire might actually be a wall of fire spell, and very few individuals would risk checking this fact. Only highly-paranoid, aware or intelligent individuals, or those who understand they face illusions, should even be allowed to examine such effects to determine their veracity. This applies equally to NPCs as well, and players are within their rights in calling out GMs who do not play fair with these rules.
A passed save shows that the ability's effect is not real, but an outline of the effect remains. A failed save indicates that the individual has completely succumbed to the illusion, and will continue to insist that it is real. Future saves are not allowed. A creature who has disbelieved an [Image] effect can communicate this disbelief to others, granting them a +4 bonus on their saves (assuming they receive them). If other creatures understand that a creature is the subject of a [Phantasm] spell, they can communicate that this is not real to them, allowing them a +4 bonus on their saves. A creature that receives personal, incontrovertible proof that such an effect is not what it seems to be, after the normal save for disbelief (and the circumstances surrounding it), is allowed an additional save. If this is also failed, the individual in question has rationalised it so thoroughly that they insist the effect is real no matter what.
Notated As: [Image]
Game Rules: These abilities create something that is perceivable by anyone who views (or hears, or smells, etc) the ability's effect and is capable of processing this perception. These abilities cannot create intelligible speech unless the ability description states otherwise, and any speech they generate must be in a language known by the user, or it will come out as gibberish. Any such perception must be familiar to the user, and it will be dependent on their subjective perceptions of such a perception.
Notated As: [Phantasm]
Game Rules: These abilities create something that only the user and the intended target or targets can perceive. It is a purely sensory effect between the user and the target, and third parties do not perceive anything where this ability's effect should be. Almost all [Phantasm] abilities are also [Mind-Affecting].
Elemental
These tags indicate what elemental energy the ability draws upon. While there are some connections between Elemental and Energy tags, but they aren't absolute.
Notated As: [Elemental: Air], [Elemental: Earth], [Elemental: Fire], [Elemental: Water]
Game Rules: These abilities have the given elemental type.
Notated As: [Elemental: Air or Earth], etc.
Game Rules: These abilities can be either elemental type, depending on the choices made when using the ability.
Notated As: [Elemental: Air or Earth], etc.
Game Rules: These abilities are of both elemental types.
Notated As: [Elemental: All]
Game Rules: These abilities are of all elemental types.
Energy
These tags indicate what type of damage the ability deals. While there are some connections between Energy and Elemental tags, they aren't absolute.
Notated As: [Energy: Acid], [Energy: Cold], [Energy: Electricity], [Energy: Fire]
Game Rules: These abilities deal only the indicated damage type unless specified otherwise in the description.
Notated As: [Energy: Acid or Cold], etc.
Game Rules: These abilities deal either type of damage. The tag changes based on the kind of damage the ability does.
Example: An ability with the tag [Energy: Cold or Fire] can deal either fire or cold damage, depending on what options are chosen. If it deals fire damage, the tag becomes [Energy: Fire], and if cold, [Energy: Cold].
Notated As: [Energy: Acid and Cold], [Energy: Acid, Cold and Fire], etc.
Game Rules: These abilities deal all of these damage types. If a creature or object affected by this ability has resistance to any of these damage types, it may only apply the lowest of all shared resistances against the given energy types.
Example: An ability with the tag [Energy: Cold and Fire] deals both cold and fire damage. A creature that has fire resistance 5 and cold resistance 5 reduces the damage from this ability by 5. A creature that has fire resistance 10 and cold resistance 5 reduces the damage by 5. A creature that has fire resistance 20 and no cold resistance does not reduce the damage from this ability.
Notated As: [Energy: All]
Game Rules: These abilities deal all energy damage types. If a creature or object affected by this ability has resistance to any of these damage types, it may only apply the lowest of all shared resistances against the given energy types.
Illumination
These tags indicate that the abilities deal with darkness or light, either filling an area with it or removing it from an area.
Notated As: [Darkness]
Game Rules: These abilities negate all [Light] abilities within their areas or on their targets, as long as these abilities aren't higher-level. The [Darkness] ability is not affected by this, and the duration of so-negated [Light] abilities continues. Any Investment costs for such abilities must continue to be paid.
Notated As: [Light]
Game Rules: These abilities negate all [Darkness] abilities within their areas or on their targets, as longa s these abilities aren't higher-level. The [Light] ability is not affected by this, and the duration of so-negated [Darkness] abilities continues. Any Investment costs for such abilities must continue to be paid.
I Need A Group Name
These tags indicate that the abilities channel positive or negative energy.
Notated As: [Negative]
Game Rules: These abilities deal negative energy damage. These affect living creatures normally, while undead receive the Inverse effect instead. Creatures that are neither living nor undead are Immune.
Notated As: [Positive]
Game Rules: These abilities deal positive energy damage. These affect undead creatures normally, while living creatures receive the Inverse effect instead. Creatures that are neither undead nor living are Immune.