Character Module Dark FX Module
How FX Work FX Components
FX Types
Using FX
Noticing FX
Countering FX
Creating FX FX Descriptions
FX Modifiers
FX Structures
Creating FX
Advancement Improving and Adding FX

FX in d20A are made up of certain basic components: each FX includes one or more effects and one or more descriptors of those effects and their source. An FX may also include one or more modifiers (Extras or Flaws) that change how the basic effect works. These components are assembled in a particular structure to create the FX.


The basic component of a supernatural ability is what the FX actually does. FX are defined in game terms with little or no regard for the actual cause of the effect, what it looks like, or how it is described. The actual mechanics, what the effect does in the game, is the important thing. This means one game-system FX may encompass a wide number of "actual" effects. For example, the Damage FX is used for anything that causes damage, which includes a tremendous variety of damaging attacks, from more powerful unarmed strikes to melee weapons, physical projectiles, harmful energy emissions, chemicals, and so forth.


Modifiers, much as you might expect, change the way basic FX work. They customize an FX, retaining most of how it works and adjusting a few things to suit a particular idea. For example, a modifier might change an FX’s default range, either improving it (allowing a normally Touch Range FX to work at a distance) or limiting it (forcing a Close Range FX to only work by touch). Modifiers that enhance FX are called Extras and increase an FX’s cost along with its capabilities. Modifiers that limit effects are called Flaws and decrease the FX’s cost as well as its capabilities. Modifiers are permanent changes to an FX, essentially creating an all-new effect out of the base FX. So a FX that needs an FX both with and without a modifier has to pay for two different FX rather than just one.

Fixed ModifiersEdit

Some modifiers provide only small or limited changes to how an FX functions, and as such modify the cost less. Fixed Extras and Fixed Flaws provide these smaller modifications.


An FX's components are put together in a particular structure, a way of assembling them to "build" an FX. The normal FX structure is simple: add up the value of the FX’s components and extras, subtract the value of its flaws to arrive at its cost per rank. Multiply by the desired rank. Add the cost of its Fixed Extras, and subtract the value of its Fixed Flaws to arrive at the final cost:

FX cost = (base cost per rank + extras – flaws) x rank + (fixed extras – fixed flaws)

The normal FX structure is used for most FX in d20A to one degree or another. However, the game also offers other FX structures that provide more flexibility, particularly the ability to reconfigure an FX during play, at the expense of certain disadvantages, additional character point cost, or both:

  • Array structures have a common “pool” of character points that are shared among a number of different FX the user can switch between from round to round. Essentially, the FX has a number of distinct “settings” that can be used one at a time. Arrays provide a way to build FX with a great deal of flexibility without a huge increase in cost.
  • Container structures group a number of FX together into a single FX and affect how flaws and other overall modifiers apply to them. They’re best suited for lots of FX grouped into a single FX and usable (or at least accessible) all at once.
  • Variable structures provide a “pool” of points much like Arrays, except those points can apply to any FX of a particular descriptor, but with a greater cost than a comparable Array. Variable structures provide the ultimate in versatility with a commensurate cost, useful for building FX with highly variable effects (often dependent on circumstances).

Power Level CapsEdit

Certain FX don't directly impact on PL-capped traits, but will in effect impact on a character's offensive or defensive power level. For instance, while the Conceal FX does not directly affect a character's Defense, it certainly means that the character will be hit less often, especially if the character has Visual Conceal. Thus, characters with this FX will have their overall power level cap for Defense and Toughness reduced. Alternatively an FX might simply impose a decreased power level cap for only that FX. This is more commonly seen in powerful Attack FX. Note, however, that in certain genres of gameplay, FX might lose some potency. If infrared goggles are commonplace, then a visual Conceal becomes that much less potent. So the GM may always feel free to reduce or even ignore the Power Level Penalties if circumstances in the game reduce or eliminate the benefits of an FX.

Power level penalties are actual reductions in the power level limits a character is permitted, so these penalties may not be “bought off” later in the game by buying additional ranks later.

FX DescriptorsEdit

The descriptor of an FX is all at once extra color and description for an FX and a vital component of the FX as far as the rules of the game are concerned. Most of the time, the descriptor is the former: a character who has Close Range Damage 5 with the Fire descriptor and a character who has Close Range Damage 5 with the Electricity descriptor will be doing largely the same things with these two FX for most of the game. The players and GM will describe their results differently, of course, but the results will be the same mechanically.

Once in awhile, however, the differences in descriptors matters. For FX like Boost, Immunity, and Nullify, the descriptors on FX matter. For instance, a Nullify FX which can nullify Fire FX can be used to counter the character with the Fire descriptor on the Damage FX, but not the one using the Electricity descriptor.

A descriptor can be used to describe many different aspects of an FX, but how much time you need to devote to descriptors depends entirely on the game. In a fantasy game, for example, the “Magic” descriptor might be sufficient for most of a wizard's spells. But if there are also spellcasting priests, then it might be helpful to further distinguish between “Arcane” and “Divine” when it comes to magic. And if you specialize further still by creating an ice mage, then you might decide that it's best to have “Arcane Ice Magic”.

Sample DescriptorsEdit

  • Allegiances: Anarchy, Chaos, Evil, Good, Justice, Law, Liberty, Tyranny
  • Elements: Air, Earth, Fire, Plant, Water, Weather
  • Energy: Acid, Chemical, Cold, Cosmic, Darkness, Electricity, Gravity, Heat, Kinetic, Light, Magnetic, Radiation, Sonic, Vibration
  • Phenomena: Colors, Dimensions, Dreams, Entropy, Ideas, Luck, Memes, Mind, Quantum Forces, Space, Thought, Time
  • Sources: Alien, Biological, Chi, Divine, Magic, Mystic, Mutant, Preternatural, Psionic, Psychic, Skill, Technology, Training

Types of DescriptorsEdit

Descriptors come in many different forms. The breakdown in this section is inexact, and deliberately so; some descriptors fall into more than one category, while others might not fall into any of these categories, being unique to that particular character or power. Still, the following are the major types of descriptors suited to d20 Advanced FX, and things to consider when creating or choosing FX for a character.


A descriptor may relate to the origin of an FX, where it comes from or what granted it to the character. For example, did he gain Speed in a scientific accident or from years of focused meditation at a secret temple to the God of Speed? An FX's origin may determine how it interacts with other FX. Some FX with the same origin might be better suited to counter each other, for example, or to work in conjunction, combining their benefits. Examples of origin descriptors include:

  • Accidental FX are the result of random chance or accident: being struck by lightning, doused in chemicals, exposed to exotic radiation, and so forth. The circumstances of an accidental origin may or may not be something others can duplicate (although some are sure to try).
  • Bestowed FX are granted by an outside agency of some sort, such as a deity, a technology, or perhaps a more powerful spellcaster. The process that bestows the FX can be as transitive as a Boost FX or the Enhanced Trait FX or effectively permanent, barring some sort of plot device or GM-created setback.
  • Invented FX are designed and created by someone, either the inventor of a particular piece of technology or the designer of a technique or technology for bestowing FX on others. These are best-suited for modern or futuristic games.
  • Magical FX are for when, well, a wizard did it. They typically rely on an understanding of or innate connection to mystical forces and laws that powerful characters can manipulate.
  • Racial FX are strange abilities that a character is granted simply by virtue of being born into a certain race. A race of elves, for instance, might all have Immunity to aging, while a race of Giants might all naturally be Large in size, and a race of potent alien psychics might all have natural Mental Communication.
  • Training FX are gained from study and practice. While many training FX are phenominal skills or esoteric abilities learned from trained masters, this origin covers any power that is learned rather than acquired in another way. It’s not necessarily limited to “skill-based” FX or feat-like traits. For example, even a Magic FX might be acquired through training and study.


An FX's source differs from its origin in that the origin is where the potential or ability to use the power comes from (where the character got the FX in the first place), while source is where the FX’s effect comes from, or where the FX draws its energy.

Comic book style superpowers answer this question with vague descriptors, since the kind of real-world energy required for many FX is staggering, requiring all super-humans to be living fusion reactors! While this may well be the case in your own setting, the assumption is that FX source is just another descriptor in most d20 Advanced games.

Source descriptors influence the effects of certain FX, such as Nullify Magic FX, which can counter FX with a magical source, whether or not their effects are magical.

Examples of FX sources include:

  • Biological FX come from the user’s own physiology, drawing power from stores of bio-chemical energy or perhaps from specialized organs or biological functions, like a squid’s ink or a skunk’s musk, which are generated biologically.
  • Cosmic FX draw upon the fabric of the universe itself or “cosmic” power sources like quasars, white holes, or the background radiation of the Big Bang. Cosmic FX are close to divine in many respects (see the following) in that they transcend earthly sources of power.
  • Divine FX come from a higher being, essentially a god or gods. Divine power is generally limited to the god(s) areas of influence and may be morally aligned, available only to wielders with an allegiance to that divinity.
  • Extradimensional FX originate outside the home dimension of the setting, from other planes or dimensions of existence. Some extradimensional FX are scientific while others are downright mystical, or even beyond into realms “man was not meant to know.”
  • Magical FX draw upon magical energies, however they might be defined in the setting. Typically, there is some sort of “magical energy” in existence that magicians and magical creatures draw upon for their FX and effects. Note that FX with a magical source are not necessarily “spells,” although they might be; a dragon’s breath might use magic to power it, or it might be biological, depending on the descriptors applied to it (in other words, how it’s defined in terms of the setting).
  • Moral FX come from an abstract morality or ideal, essentially from an allegiance to that ideal. Whether or not the moral FX is aware and capable of interaction is up to the GM and the specifications of the setting; it’s the character’s belief in that ideal that matters so far as the FX is concerned. “Good” and “evil” are common abstract moral sources of FX, but others may include chaos, law, anarchy, order, justice, balance, neutrality, reason, and so forth.
  • Psionic FX are effects of the mind, coming from the psyche of the wielder (or perhaps from the Collective Unconscious, which acts as a “wellspring” of psionic power). This source is associated with classic “mental” FX like Telepathy and Telekinesis, although those FX can also come from other sources.
  • Technological FX are the result of technology, machines and technological devices. Although technological power sources often involve Devices or Equipment, they don’t necessary have to; a technological FX may be a permanent implant, for example, without the limitations of a Device, but still technological (and affected by things keyed to the technological descriptor).


An FX’s medium is what the FX uses to accomplish its effect(s). Often, an FX’s source and medium are one and the same: a psionic FX uses psionic energy to power and accomplish its effects, likewise, a divine FX often uses divine energy to power and accomplish its effects.

In some cases, however, source and medium may differ and the distinction may be significant. For example, the ability to throw fireballs granted by the God of Fire is a bestowed origin, divine source, and uses fire as the medium to cause its Damage effect.

Medium descriptors generally fall into either material or energy: material mediums are substances, ranging from things like air (or other gases), water (or other liquids), and earth (soil, rock, sand, etc.) through to biological materials like acids, blood, and so forth. Energy mediums are different forms of energy, from electromagnetic (electricity, light, radio, radiation, etc.) to gravity, kinetic energy, or an exotic source like divine, magical, or psionic energy (given under Origin descriptors).


Lastly, an FX’s result is what occurs when the FX is used beyond just the game mechanics of its effect. For example, the rules of Inflict describe the penalties suffered by the entangled or helpless target, but they don’t describe the result, the nature of the affliction itself. For an Inflict that describes a sort of snare, is it glowing bonds of energy, chains of ice, the target sinking into rapidly hardening quicksand, or any number of other things?

Result descriptors tend to be fairly broad, given the potential range of results available to effects in the game. Some FX may not have or need result descriptors; after all, “Mind Control” is a pretty clear description of a result. However, “an induced trance where the human brain becomes capable of accepting neurolinguistic programming inputs” is also a valid result for that same effect.

Like medium descriptors, result descriptors may or may not match others the FX already has. Take a taser-like weapon able to stun the nervous system of its target: it has an invented origin (someone designed and built it), a technological source (it’s a technological device with a battery), uses a energy medium (an electrical shock), and results in an electrical overload of the target’s nervous system (the result descriptor for its Inflict (Action) effect). This tells us a lot about that particular FX and reasonable ways it might interact with other effects.

Applying DescriptorsEdit

Applying descriptors to a FX is as simple as describing what the FX is and how it works: “The divinely-granted ability to heal through a laying-on of hands,” for example, “or the mutant power to control magnetic fields to move ferrous metal objects.” Considerably more evocative and descriptive than “Healing effect” or “Move Object, Limited to Ferrous Metals,” aren’t they?

Generally, you should feel free to apply whatever descriptors seem appropriate and necessary to describe your character’s FX, so long as they don’t significantly change how they work in game terms. This is the key element. While descriptors may imply certain interactions or minor benefits or drawbacks, they shouldn’t significantly change how an effect works, that’s the role of FX feats, modifiers, and drawbacks. So, for example, “area” is not a descriptor, it is an extra you apply to allow an FX to affect an area rather than a single target.

Applying Descriptors in PlayEdit

While descriptors are generally applied to FX when those FX are acquired (that is, when a character is created), in some cases, certain descriptors may be left unspecified, to be defined during play. This can either be because nobody thought to define the descriptor in advance, or it was deliberately left vague, to be filled-in later.

So, for example, a particular character might not know the origin or source of her FX, and her player doesn’t want to know, leaving them a mystery for later development in the game. The GM agrees and so the character's FX have no origin or source descriptors. Instead, the GM chooses them, which isn’t known until the character is subject to an anti-magical field and discovers her FX don’t work! The GM awards the player a hero die for the unexpected setback and now the source of the character's FX is known, although their origin still remains a mystery...

Applying descriptors in play gives you a lot of flexibility, letting you handle certain things “on the fly” rather than having to describe every aspect of a character in excruciating detail beforehand. The key tool for handling the application of descriptors in play is the use of hero dice. If applying a new descriptor is a setback for the character, then award the player a hero die, just like any other setback. If the new descriptor is chosen by the player and gives the character a minor advantage, you might ask the player to pay a hero die for the privilege, although you can balance this with an immediate hero die award for the clever idea, if you want (making the hero die a token expenditure). If it’s neither, then there’s no hero dice cost, just apply the descriptor.

Changing Descriptors in PlayEdit

On some occasions, you or a player may wish to change a particular descriptor during the course of the game, removing an existing descriptor and possibly replacing it with another one.

Sometimes this takes the form of discovering that a descriptor the character thought applied actually does not, such as a character discovering his “magical” FX are actually the mutant ability to manipulate reality in certain ways. So long as the change doesn’t contradict any previously introduced information, this is no different than applying a descriptor in play, and should be handled in the same way. On the other hand, if other effects previously worked on the character as if his FX were magical, then some sort of explanation is required. The Gamemaster may wish to limit or ban “discovering” a descriptor that has already been established, although it might still be changed.

Changing descriptors is best handled as a plot device, much like re-allocating character points and redesigning characters. If exposure to strange magical forces changes a character’s FX source from biological to magical, for example, that’s something for the GM to decide in the context of the game. Like with defining descriptors in play, if a change in descriptors through GM Fiat constitutes a setback, the GM should award the player a hero die. Changes that provide an advantage don’t cost, however, since the GM chooses when and where they occur.

Temporarily changing a descriptor can be a use of extra effort, like any other FX stunt. For example, a character might change the result of an electrical Damage effect to a magnetic Move Object effect for one use. This is like any other FX stunt and the changed or additional descriptors are an important part of the stunt. Sometimes an FX stunt may change nothing but an effect’s descriptor(s), such as changing a Damage effect from laser-light to a gamma-ray “graser” or from heat to cold. The GM decides what constitutes a reasonable change in descriptors for an FX stunt, based on the FX’s existing descriptors and effects.

Required DescriptorsEdit

In some campaign settings, the Gamemaster may require certain descriptors for all FX. Usually, a required descriptor reflects some common element of the campaign. For example, if all characters with FX are mages, then all FX have the “mutant” descriptor, unless the player comes up with a good explanation why they shouldn’t. If all superhumans are psychic mutants, then all FX have both the “psychic” and “mutant” descriptors.

Likewise, if all FX derive from quantum forces in some way, “quantum” might be a required descriptor. The GM sets the rules as far as what descriptors are required (or restricted) in the campaign.

"Natural" FXEdit

FX in d20A refer to all extraordinary traits other than Ability Scores, skills, and feats. Whether a character with FX is "supernatural" or not is largely a matter of opinion. For example, there are lots of fictional characters with supernatural traits still considered “normal” humans. Their amazing FX come from talent, training, self-discipline, devices, or some similar source, with appropriate descriptors. They’re still FX in game terms, but they don’t necessarily mean the character is something other than human.

Ultimately it’s up to the GM to decide if having certain effects makes a character something “other than human,” (and what, if anything, that means) depending on the nature of FX in the campaign setting.