All forms of magic are fundamentally the same, even when their methods are wildly different. Whether it takes the form of arcane or divine spells, psionic powers, eldritch invocations, or some other ability, these systems of magic are collectively called Esoterica and their individual magics (spells, powers, etc.) are collectively called Esoteric Effects. Anytime these terms are used, the text is referring to all forms of magic abilities, regardless of source.
Casting Esoteric Effects
Magic spells, psionic powers, and most other esoteric abilities are a one-time magical effect. Despite different ways that characters use to learn these effects, they are very similar when it comes to casting them. Spells and similar abilities all work in the same basic way.
Choosing an Esoteric Effect
First you must choose which effect to cast. Different systems with have different ways of selecting an effect, such as by referencing a spellbook or even simply just knowing the effect.
To cast an effect, you must be able to speak (if it has a verbal component), gesture (if it has a somatic component), and manipulate the material components or focus (if any). Additionally, you must concentrate to cast an effect.
If an effect has multiple versions in its description, you choose which version to use when you cast it. You don’t have to prepare or learn a specific version of an effect when multiple versions are described within that effect.
Concentration
To cast an effect, you must concentrate. If something interrupts your concentration while you’re casting, you must make a concentration check or fail to cast the effect. The more distracting the interruption and the higher the level of the effect you are trying to cast, the higher the concentration check DC is. (Higher-level powers require more focus and effort.) If you fail the check, you lose the effect just as if you had cast it to no effect, losing whatever resource you were using to cast (spell slot, power points, and so forth).
When you make a concentration check, you roll d20 and add your Caster Level and Key Ability Modifier for that esoteric effect.
Injury
If you take damage while trying to cast an effect, you must make a concentration check (DC 10 + points of damage taken + the level of the effect you’re casting). If you fail the check, you lose the esoteric effect. The interrupting event strikes during casting if it comes between when you start and when you complete casting the effect (for an effect with a casting time of 1 full round or more) or if it comes in response to your casting the effect (such as an attack of opportunity provoked by the effect) or a contingent attack (such as a readied action).
If you are taking continuous damage, half the damage is considered to take place while you are casting an effect. You must make a concentration check (DC 10 + ½ the damage that the continuous source last dealt + the level of the effect you’re casting). If the last damage dealt was the last damage that the effect could deal, then the damage is over and does not distract you.
Repeated damage does not count as continuous damage.
Esoteric Effect
If you are affected by a spell, power, or other esoteric effect while attempting to cast an effect of your own, you must make a concentration check or lose the effect you are casting. If the effect affecting you deals damage, the DC is 10 + the damage taken + the level of the effect you’re casting.
If the effect interferes with you or distracts you in some other way, the DC is the effect’s saving throw DC + the level of the effect you’re casting. For an effect with no saving throw, it’s the DC that the effect’s saving throw would have if a save were allowed (10 + effect level + caster’s ability score).
Grappling or Pinned
Casting a spell while you have the grappled or pinned condition is difficult and requires a concentration check (DC 10 + the grappler’s CMB + the level of the effect you’re casting). Pinned creatures can only cast effects that do not have somatic components.
Vigorous Motion
If you are riding on a moving mount, taking a bouncy ride in a wagon, on a small boat in rough water, below-decks in a storm-tossed ship, or simply being jostled in a similar fashion, you must make a concentration check (DC 10 + the level of the effect you’re casting) or lose the effect.
Violent Motion
If you are on a galloping horse, taking a very rough ride in a wagon, on a small boat in rapids or in a storm, on deck in a storm-tossed ship, or being tossed roughly about in a similar fashion, you must make a concentration check (DC 15 + the level of the effect you’re casting) or lose the effect.
If the motion is extremely violent, such as that caused by an earthquake, the DC is equal to 20 + the level of the effect you’re casting.
Violent Weather
You must make a concentration check if you try to cast an effect in violent weather. If you are in a high wind carrying blinding rain or sleet, the DC is 5 + the level of the effect you’re casting. If you are in wind-driven hail, dust, or debris, the DC is 10 + the level of the effect you’re casting. In either case, you lose the effect if you fail the concentration check. If the weather is caused by an esoteric effect, use the rules in the Esoteric Effect subsection above.
Casting Defensively
If you want to cast an effect without provoking any attacks of opportunity, you must make a concentration check (DC 15 + the level of the effect you’re casting) to succeed. You lose the effect if you fail this check, but you do not provoke an attack.
Entangled
If you want to cast an effect while entangled in a net or by a tanglefoot bag or while you’re affected by magic with similar effects, you must make a concentration check (DC 15 + the level of the effect you’re casting) to cast the effect. You lose the effect if you fail.
Caster Level
An effect’s power often depends on its caster level, which for most characters is equal to your class level in the class you’re using to cast the effect.
You can cast an effect at a lower caster level than normal, but the caster level you choose must be high enough for you to cast the effect in question, and all level-dependent features must be based on the same caster level.
In the event that a class feature, domain granted power, or other special ability provides an adjustment to your caster level, that adjustment applies not only to effects based on caster level (such as range, duration, and damage dealt) but also to your caster level check to overcome your target’s spell resistance and to the caster level used in dispel checks (both the dispel check and the DC of the check).
Caster Level Checks
To make a caster level check, roll 1d20 and add your caster level (in the relevant class). If the result equals or exceeds the DC (or the spell resistance, in the case of caster level checks made for spell resistance), the check succeeds.
Key Ability
The ability score that your esoteric effects depend on—your Key Ability Score—is related to what class (or classes) you have levels in. The modifier for your esoteric ability is referred to as your Key Ability Modifier. If your key ability score is 9 or lower, you can’t cast esoteric effects that rely on that ability score.
Your key ability modifier is typically added to the save DC of an esoteric effect, making the effect harder to resist.
A high key ability score also grants bonus spells, bonus power points, and other similar benefits related to your character class.
Effect Failure
If you ever try to cast an effect in conditions where the characteristics of the effect cannot be made to conform, the casting fails and the effect is wasted.
The Effect’s Result
Once you know which creatures (or objects or areas) are affected, and whether those creatures have made successful saving throws (if any were allowed), you can apply whatever results an effect entails.
Special Esoteric Effects
Many special effects are handled according to the school or discipline of the effect in question. Certain other special features are found across esoteric effects.
Attacks
Some effect descriptions refer to attacking. All offensive combat actions, even those that don’t damage opponents are considered attacks. Attempts to turn or rebuke undead count as attacks. All effects that opponents resist with saving throws, that deal damage, or that otherwise harm or hamper subjects are attacks. Effects that summon monsters or other allies are not attacks because the spells themselves don’t harm anyone.
Bonus Types
Usually, a bonus has a type that indicates how the effect grants the bonus. The important aspect of bonus types is that two bonuses of the same type don’t generally stack. With the exception of dodge bonuses, most circumstance bonuses, and racial bonuses, only the better bonus works (see Combining Magical Effects). The same principle applies to penalties—a character taking two or more penalties of the same type applies only the worst one.
Bringing Back the Dead
Several effects have the power to restore slain characters to life.
When a living creature dies, its soul departs its body, leaves the Material Plane, travels through the Astral Plane, and goes to abide on the plane where the creature’s deity resides. If the creature did not worship a deity, its soul departs to the plane corresponding to its alignment. Bringing someone back from the dead means retrieving his or her soul and returning it to his or her body.
Negative Levels
Any creature brought back to life usually gains one or more permanent negative levels. These levels apply a penalty to most rolls until removed through spells such as restoration. If the character was 1st level at the time of death, he loses 2 points of Constitution instead of gaining a negative level.
Preventing Revivification
Enemies can take steps to make it more difficult for a character to be returned from the dead. Keeping the body prevents others from using raise dead or resurrection to restore the slain character to life. Casting trap the soul prevents any sort of revivification unless the soul is first released.
Revivification against One’s Will
A soul cannot be returned to life if it does not wish to be. A soul knows the name, alignment, and patron deity (if any) of the character attempting to revive it and may refuse to return on that basis.
Combining Magical Effects
For combining the effects of multiple effects, refer to the rules on Combining Magical Effects.