Native Sons
A creature on its home plane is never considered extraplanar. A spellcaster cannot banish a tanar'ri from its home plane of the Abyss. Spells like binding, blasphemy, dispel evil, holy word, and planar binding have reduced or negated effectiveness against creatures native to the plane that they are cast on. Note that Prime Material natives are a strange exception to this rule; no matter where they stand, they are never considered extraplanar (although this does not make them natives of the plane they are standing on, either).

Connected Planes
Planewalking wizards and sorcerers have a lot to remember. Certain spells use the Astral or the Ethereal Planes to work. Both planes are accessible from the Prime Material, but this isn't true everywhere. If an Astral-linked spell is cast on a plane where the Astral Plane isn't accessible, the spell fails.
It's easy enough to figure out if these two planes (also called planar pathways) are accessible or not. All of the Outer Planes are connected to the Astral Plane, but none of the Inner Planes are. Similarly, all of the Inner Planes are connected to the Ethereal Plane, but none of the Outer Planes are.
On all planes but the Prime Material, spells that summon creatures can only call up monsters native to the plane on which the spell is cast, or on a directly adjoining plane. The gate spell is an exception to this rule.
Elementals: Elemental summonings are altered because of this principle as well. When a character uses a spell key to summon an elemental on an Outer Plane, she draws upon the forces on whatever plane she's on to create the elemental. The "elemental" takes on some of the aspects of the plane from which it's created, including alignment. It will refuse to act in contradiction of its alignment, and may or may not be entirely trustworthy.

Extra Dimensions
These spells and magical items create extradimensional spaces. Normally, using extra dimensions isn't a problem – unless a character is on the Astral Plane, where there aren't any extra dimensions. There is also a chance that some unusual areas, such as a few of the demiplanes in the Ethereal Plane, might also be completely cut off from the extradimensional world.

Spells with Planar Pathways

Ethereal Blink Create Greater Undead Ή ² Create Undead Ή ² Elemental Swarm ² Energy Drain ² Enervation Ethereal Jaunt ² Etherealness ² Greater Restoration ² Greater Shadow Conjuration Greater Shadow Evocation Leomund's Secret Chest Lesser Planar Ally ² Lesser Planar Binding Restoration ² Phase Door ² Shades Shadow Conjuration Shadow Evocation Shadow Walk All element-based Conjuration [Summoning] spells

Astral Astral Projection Dimension Door Divination Ή ² Duo-Dimension Raise Dead ² Reincarnate ² Resurrection ² True Resurrection ² Vision Dual Augury Ή ² Banishment Ή Commune Ή ² Contact Other Plane Ή ² Dismissal Ή ² Drawmij's Instant Summons Ή Greater Planar Ally Ή ² Greater Planar Binding Ή Planar Ally Ή ² Planar Binding Ή Summon Monster I – IX Ή ²

Extradimensional Dimensional Anchor Ή ² Leomund's Secret Chest Maze

Mordenkainen's Magnificent Mansion Rope Trick

Ή May or may not cross planar pathways, depending on the creature targeted or the home plane of the caster's deity.
² When cast as divine magic, these spells are unaffected by planar pathways. They are affected only if cast as an arcane spell or used through a scroll or other magical item.

Divine Realms
The powers dictate the magical conditions in their own realms, imposing penalties and benefits as they see fit. Conditions of the surrounding plane may be completely absent, or they may be twice as potent. These conditions utterly depend on the nature of the deity who controls the realm, and may not be overcome save by the deity's own whim.

Alterations by School
Arcane spellcasters must also deal with the changes that occur to the various schools of magic on certain planes (divine spellcasters ignore these changes). Each plane has its own set of physical laws and interactions with the forces of magic. Certain schools of magic can be nulled, enhanced, diminished, or somehow altered.

• Nullified spells and schools don't work on a given plane – they simply fail when cast. These are usually based on elemental or philosophical opposites. For example, water spells never work on the Plane of Fire. Certain "null" spells may be restored with spell keys, such as Chaos spells on Mechanus.
• Diminished spells function at one level lower than normal. This occurs when a plane's composition and physics aren't conducive to that particular school of magic, but not to the degree that the spells cannot function at all. Spells of 5th level or higher in a diminished school cannot be cast at all.
• Enhanced spells always function as though cast by a character one level higher than the caster's actual level. This happens on planes where that type of spell is conducive to the environment due to similarity or general fostering of such effects; for example, violent evocations on Gehenna mirror the violence of the plane.
• By far the most common change to arcane spells are alterations in their appearance or effects. These altered effects vary so much that they generally rely upon the DM's creativity. Sometimes only the appearance of a spell's effect changes, while other times, the general nature of a spell itself changes.

School Alterations by Plane

For the most part, these alterations only apply to arcane spells. Note that special exceptions do appear.

The Astral Plane

Conjuration – Spells of this school are diminished. Summoning spells call upon creatures from the Prime Material and all Outer Planes. Elementals cannot exist on the Astral Plane (there are no spell keys to change this).

Divination – Everything radiates magic on this plane, so detect magic is useless.

Enchantment – Mind-influencing spells are enhanced.

Illusion – There is a 30% chance that figments and shadows take the form of random floating thoughts instead of the intended illusion.

Transmutation – Spells dealing with only physical matter (eg disintegrate), or affecting solid ground (eg Evard's black tentacles, move earth), are nullified.

Special – The Astral Plane has no link to the Ethereal and Inner Planes and no extradimensional spaces. Spells that manipulate time (eg time stop) are nullified without a spell key.

The Ethereal Plane

Abjuration – Spells of this school are diminished.

Conjuration – Summoning spells call upon creatures from the Inner Planes, the Prime Material, or the demiplanes.

Divination – Spells of this school are nullified.

Illusion – Spells of this school are enhanced. Illusions last without concentration, then gradually fade into nothingness. There is a 1 in 20 chance of any figment or shadow taking on a life and reality of its own, beyond the caster's control.

Special – Earth spells are diminished, because ethereal protomatter is rarely completely solid. Water spells are enhanced in the fluid ethereal fogs. The Ethereal Plane has no link to the Astral and Outer Planes.

The Inner Planes

The Elemental Plane of Air

Conjuration – These spells can only draw creatures from the planes of Air, Smoke, Ice, Lighting, and Vacuum. Creatures native to the plane of Air aren't automatically controlled by the caster of Summon Monster spells.

Special – Air spells are enhanced; all other elemental spells are diminished.

The Elemental Plane of Earth

Conjuration – These spells can only draw upon creatures found on the planes of Earth, Ooze, Mineral, Magma, and Dust.

Special – Earth spells are enhanced; all other elemental spells are diminished.

The Elemental Plane of Fire

Conjuration – These spells can only summon creatures from the planes of Fire, Magma, Smoke, Radiance, and Ash.

Special – Fire spells are enhanced; water spells are nullified; all other elemental spells are diminished.

The Elemental Plane of Water

Conjuration – These spells can only summon creatures from the planes of Water, Ooze, Steam, Ice, and Salt.

Special – Fire spells are nullified; water spells are enhanced; all other elemental spells are diminished.

The Paraelemental Plane of Ice

Conjuration – These spells can only summon creatures from the planes of Air, Lightning, Salt, Steam, Vacuum, and Water.

Special – Earth and fire spells are diminished. Cold-based spells are nullified (it can't get any colder).

The Paraelemental Plane of Magma

Conjuration – These spells can only summon creatures from the planes of Ash, Dust, Earth, Fire, Mineral, and Radiance.

Special – Air and water spells are diminished.

The Paraelemental Plane of Ooze

Conjuration – These spells can only summon creatures from the planes of Earth, Dust, Mineral, Ooze, Salt, Steam, and Water.

Special – Air and fire spells are diminished.

The Paraelemental Plane of Smoke

Conjuration – These spells can only summon creatures from the planes of Air, Ash, Fire, Lighting, Radiance, Smoke, and Vacuum.

Special – Earth and water spells are diminished.

The Quasielemental Plane of Lightning

Conjuration – These spells can only summon creatures from the planes of Air, Ice, Lightning, Positive Energy, Radiance, and Smoke, Steam.

Special – Air spells are enhanced; earth spells are diminished; water spells are altered. Invisibility spells are useless, as St. Elmo's Fire outlines all things.

The Quasielemental Plane of Mineral

Conjuration – These spells can only summon creatures from the planes of Earth, Magma, Ooze, Positive Energy, Radiance, and Steam.

Special – Air and fire spells are diminished; earth spells are enhanced; water spells are altered.

The Quasielemental Plane of Radiance

Conjuration – These spells can only summon creatures from the planes of Fire, Lightning, Magma, Mineral, Positive Energy, Radiance, and Smoke.

Special – Fire spells are enhanced; water spells are diminished. Darkness and deeper darkness creates only weak shade.

The Quasielemental Plane of Steam

Conjuration – These spells can only summon creatures from the planes of Ice, Lightning, Mineral, Ooze, Positive Energy, Steam, and Water.

Special – Fire spells have half effect (none with a successful save); water spells are enhanced.

The Quasielemental Plane of Ash

Conjuration – These spells can only summon creatures from the planes of Ash, Dust, Fire, Magma, Negative Energy, Smoke, and Vacuum.

Special – Air spells are altered; fire spells of greater than instantaneous duration are nullified; water spells are altered.

The Quasielemental Plane of Dust

Conjuration – These spells can only summon creatures from the planes of Ash, Dust, Earth, Magma, Negative Energy, Ooze, and Salt. Solid objects have a maximum duration of 1d4 Χ 10 minutes before crumbling to dust, unless protected by a wall of force spell to bind the material into place.

Special – Air spells are altered; water spells are diminished.

The Quasielemental Plane of Salt

Conjuration – These spells can only summon creatures from the planes of Dust, Ice, Negative Energy, Ooze, Vacuum, and Water.

Special – Water conjured on this plane is undrinkable, and water and ice have a maximum duration of 1d4 minutes before evaporating.

The Quasielemental Plane of Vacuum

Conjuration – These spells can only summon creatures from the planes of Air, Ash, Ice, Negative Energy, Salt, and Smoke.

Special – Air spells are nullified, as are fire spells of greater than instantaneous duration.

The Positive Energy Plane

Conjuration – These spells can only summon creatures from the planes of Lightning, Mineral, Radiance, and Steam. Any physical material conjured here is destroyed in one round, exploding in a burst of harmless light.

Special – Fire magic is enhanced. Spells that inflict damage always inflict the minimum possible amount; life-sustaining spells have the maximum duration and effect.

The Negative Energy Plane

Conjuration – These spells can only summon creatures from the planes of Ash, Dust, Salt, and Vacuum. Physical materials conjured here crumbles to nothingness in a single round.

Special – Air and fire spells are diminished. Spells that cause damage always inflict the maximum possible amount; life-sustaining spells have the minimum duration and effect.

The Outer Planes

The Abyss

Conjuration – These spells can only summon creatures from the planes of the Abyss, Astral, Carceri, the Outlands, and Pandemonium. Summoning spells have a chance of being answered by a powerful tanar'ri (10% per spell level).

Divination – Abyssal lords and true tanar'ri gain an immediate Scry check with a +10 bonus when observed by these spells (DC same as spell). If successful, the tanar'ri can use the spell to attack the caster with spells of a related form to the divination. For example, clairaudience would allow a sonic attack; clairvoyance would allow visual attacks; detect evil would allow mind-influencing attacks; and detect magic allows any magical spell.

Illusion – Spells of this school are enhanced.

Necromancy – Spells that create undead allow petitioners, manes, and other lesser creatures to take over the bodies and attack the caster. Reincarnation always returns the target as a tanar'ri (usually a dretch or manes, but rarely a rutterkin or lesser tanar'ri).

Transmutation – The caster must make a Will save (DC 10 + spell level) when casting these spells. If he succeeds, the spell works normally. If he fails, the spell is corrupted to create an evil, warped, or useless effect.

Special – Chaotic and evil spells are enhanced. Good and lawful spells are diminished. Destructive elemental spells are enhanced, but elemental spells require a Will save (DC same as spell) to avoid failure each time they have a protective effect.

Detect thoughts destroys the minds of casters who read the minds of tanar'ri in the Abyss. The caster must make a Will save (DC 10 + half of fiend's HD + fiend's Cha bonus). Success means that the caster is feeblemind for 2d6 hours, and can relate useful information when he recovers. Failure means that the caster suffers from madness (of a type agreed upon by the player and the DM) and immediately loses a number of spell levels equal to the fiend's CR (half of these levels are lost permanently).

Acheron

Conjuration – These spells can only summon creatures from the planes of Acheron, the Astral, Baator, Mechanus, and the Outlands. Summoned creatures must obey every command, even suicidal ones. However, for each creature summoned, the caster must provide a petitioner or planar in exchange. The intended sacrifice receives a Will save (same DC as spell) to avoid the effect. If the sacrifice saves, the caster must make a Will save to avoid the same effect. If both sacrifice and caster save, the spell fails.

Divination – These spells can never be used to spy on opposing military forces. Omens are often skewed to show the worst possible result. Any positive or negative omen always applies to the entire group that the caster belongs to.

Necromancy – If the caster's level or Hit Dice are equal to or greater than the target of these spells, they works normally. If the caster's level or HD is less than that of the intended target, the spell fails, and the caster loses hit points equal to the spell level + caster level.

Special – Chaotic spells are diminished; lawful spells are enhanced.

Arborea

Conjuration – Except in the realm of Amun-Thys, all summon monster spells are answered by animal spirits.

Divination – These spells require entrails to read, omens to interpret, or signs and portents drawn from the stars. Thus, all casting times are increased: single-action spells require one full round to cast; other spells require +1 time increment (round, minute, hour, etc) to cast.

Enchantment – Mind-affecting spells related to emotions are enhanced. However, if the target saves with a roll of 1–4, the target attacks the caster in a berserk rage, with a +2 morale bonus to attack and damage (lasting until the target suffers a wound).

Necromancy – Spells of this school are nullified. Within divine realms, these spells work if approved of by specific gods (Hecate in Olympus, Labelas and Corellon in Arvandor, Nephythys in Pelion, etc).

Special – Evil and lawful magic is diminished; chaotic and good spells are enhanced. Elemental spells require spell keys, except for air spells in Arvandor and water spells in Ossa.

Arcadia

Conjuration – These spells can only summon creatures from the planes of Arcadia, the Astral, Mechanus, Mount Celestia, and the Outlands. If used for a noble purpose or for the greater good, summoned creatures serve willingly and to the best of their ability. If used for selfish reasons, summoned creatures resist the caster's control whenever possible. Natural animals of Arcadia aren't affected by conjuration spells cast by Primes.

Enchantment – All creatures gain a +2 bonus to Will saves vs. compulsion spells. If the target makes the save, the caster must make a normal Will save or fall under the control of the intended target.

Illusion – Natives of Arcadia are immune to illusions. All others gain a +2 bonus to save.

Necromancy – Spells of this school are nullified.

Special – Chaotic spells are diminished; lawful spells are enhanced.

Baator

Conjuration – These spells can only summon creatures from the planes of Acheron, the Astral, Baator, Gehenna, and the Outlands. Summoning spells on Baator require a rigorous ritual, taking one minute per spell level and a Spellcraft check (DC 15). If the binding is not perfect, the summoned creature is under no obligation to obey the caster.

Divination – These spells usually present results in the worst possible light, although there is always a kernel of truth. However, roaming fiends are always drawn by divination spells.

Necromancy – Spells of this school are enhanced.

Special – Chaotic and good spells are diminished on Baator; evil and lawful spells are enhanced.

The Beastlands

Conjuration – These spells can only summon residents of the Beastlands (typically celestial animals) or pseudoelementals (with a spell key). Furthermore, summoned beasts and magical animals cannot be controlled by the caster.

Divination – Spells that call upon other-planar knowledge or contact beings on other planes do not function in the Beastlands.

Enchantment – All animals on the Beastlands are considered magical animals, and may not be affected by spells that affect animals only.

Necromancy – Spells of this school are diminished.

Transmutation – Spells that manipulate the wind, air, or weather are nullified, as are all spells and spell-like effects that provide the power of flight.

Special – All air spells are nullified. Fire spells are enhanced in Krigala but diminished in Karasuthra. Earth spells are enhanced near mountains or large rocky outcroppings, and water spells are enhanced near large bodies of water.

Bytopia

Conjuration – Only items and creatures that already exist on Bytopia can be conjured or summoned. Note that Bytopia is a plane of artisans and craftsmen, but not of mechanised machinery.

Divination – All spells of this school must involve the elements of the plane or its products as an arcane focus. For example, a clairvoyance spell could be cast by looking in a pool of water or a Bytopian mirror; clairaudience could be cast by the caster placing his ear against the ground.

Necromancy – Spells of this school are diminished.

Special – Good spells are enhanced; evil spells are diminished. All elemental spells are enhanced in Shurrock, although spells with wide-ranging effects (control water, control weather, earthquake, etc) must overcome Spell Resistance 20.

Carceri

Conjuration – These spells can only summon creatures from the planes of the Abyss, the Astral, Carceri, the Grey Waste, and the Outlands. Summoned creatures are not bound by the caster. If the caster fails to offer some bribe, intelligent creatures usually turn on him.

Divination – Spells of this school require that a comrade's blood be spilled and the spreading pool of blood used as an arcane focus.

Necromancy – Spells of this school are enhanced.

Transmutation – These spells always create the most evil result possible. If the spell can't actually produce evil, it manifests itself in a hostile and horrible way.

Special – Evil spells are enhanced; good spells are diminished. Air spells are enhanced in Minethys; Earth spells are enhanced in Colothys; Water spells are enhanced in Agathys and Porphatys. Otherwise, all elemental spells are diminished.

Elysium

Conjuration – These spells can only summon creatures from the planes of the Astral Plane, Bytopia, the Beastlands, or the Outlands. Pseudoelementals (summoned with a spell key) are free to do as they wish, but are always of neutral good alignment and serve willingly in the service of good. Natives are never summoned by spells of this school, and other nonnatives of good alignment receive a +4 bonus to saving throws.

Enchantment – Natives are immune to compulsion spells of this school, and other nonnatives of good alignment receive a +4 bonus to their saving throws.

Illusion – Spells that serve to obscure, hide, or falsify information are nullified.

Necromancy – Spells of this school are nullified, and have a 2 in 6 chance of affecting the caster instead.

Special – Good spells are enhanced; evil spells are nullified. Water spells are enhanced in Thalasia.

Gehenna

Conjuration – These spells can only summon creatures from the planes of the Astral, Baator, Gehenna, the Grey Waste, and the Outlands. Summoning spells on Gehenna require a rigorous ritual, taking one minute per spell level and a Spellcraft check (DC 15). If the binding is not perfect, the summoned creature is under no obligation to obey the caster. Spells can only draw creatures native to Gehenna; even Gate can't break this planar boundary.

Divination – To cast a spell of this school, the caster must capture an enemy, stake it out on the ground, and perform the divination in the entrails of the foe.

Enchantment – Spells of this school are diminished.

Evocation – Spells of this school are enhanced.

Necromancy – Spells of this school are enhanced.

Special – Evil spells are enhanced; good spells are diminished. Earth and Fire spells are enhanced on Khalas and Chamada; Fire spells are nullified on Krangath, and Water spells are nullified on Chamada and Mungoth.

The Grey Waste

Conjuration – These spells can only summon creatures from the planes of the Astral Plane, Carceri, Gehenna, the Grey Waste, and the Outlands. Summoning spells can call upon any creature, regardless of power level – a 1st-level spell might summon a pit fiend. Spells usually call one of the skirmishing warriors in Oinos, who keep note of the caster and may return for revenge in future.

Divination – The Waste twists spells to cause despair and angst in the caster. The result may be true or false, since the plane doesn't differentiate between truth and lies.

Enchantment – Targets of mind-affecting spells gain a +3 bonus to Will saves. If the spell is successful, it snaps the target out of the Grey Waste's influence upon its expiration; the target's anger at being manipulated shields him from the Waste for one week. However, after this time the target automatically fails his next save against the Waste's spiritual numbing. This side-effect doesn't influence targets who have been numbed for more than two weeks.

Necromancy – The number of undead that a caster can control is not restricted by his level. All undead created on the Grey Waste are intelligent and free-willed.

Transmutation – Spells that grant special properties to items, such as magic weapon, are enhanced, provided that they could conceivably be used for an evil purpose. If the spell can only be used for good, it is nullified.

Special – Evil spells are enhanced; good spells are nullified. Colour-based magic is nullified. Teleport and similar spells are nullified on Oinos.

Limbo

In order to cast a spell of any school in Limbo, the caster must succeed in a Concentration check (DC 15). If he succeeds, the spell works normally. Otherwise, the spell fails; if it was cast in the primal chaotic soup, it surges with a random magical effect (determined by the DM or by a roll on the rod of wonder table).

Conjuration – These spells can only summon creatures from the planes of the Astral, Limbo, the Outlands, Pandemonium, or Ysgard. Creatures interpret the caster's instructions as loosely as possible, and have extremely sgort attention spans.

Divination – The caster must make a Will save (DC same as spell) in order to interpret the chaotic results of these spells.

Illusion – Figments and shadows have a 2 in 20 chance of becoming permanently real.

Transmutation – These spells may be modified in appearance or effect if the caster fails a Spellcraft check (DC same as spell). The nature and degree of the modification is determined by the DM, and should be more extreme if the Spellcraft check was failed badly.

Special – Chaotic spells are enhanced, and have additonal random effects (determined by the DM or by a roll on the rod of wonder table). Elemental spells are enhanced. Lawful spells are nullified. Wish and limited wish spells are interpreted very loosely and frivolously.

Mechanus

Conjuration – These spells can only summon creatures from the planes of Acheron, Arcadia, the Astral, Mechanus, and the Outlands. Anything summoned in Mechanus has no choice but to obey the caster. Only lawful creatures may be summoned. Chaotic spellcasters can expect summoned creatures to obey only the letter of their commands.

Divination – Spells cast by a chaotic caster are nullified.

Illusion – Spells of this school are nullified, and create little more than wispy outlines that fool no-one.

Necromancy – Spells of this spell cause the caster to lose hit points equal to the spell level + caster level; otherwise, they have normal effect.

Special – Chaotic spells are nullified; lawful spells are enhanced.

Mount Celestia

Conjuration – These spells can only summon creatures from the planes of Arcadia, the Astral, Bytopia, Mount Celestia, and the Outlands. Lawful or good creatures serve faithfully, but chaotic, neutral, or neutral creatures gain an additional Will save for every action they are required to take. Chaotic or evil summoners can't compel any summoned creature to obey them.

Divination – All spells of this school are true and accurate.

Necromancy – Spells of this school have the opposite of their usual effect upon the intended target (eg, damaging spells cause healing).

Special – Chaotic and evil spells are diminished; good and lawful spells are enhanced.

The Outlands

Conjuration – These spells can only summon creatures from the Astral Plane and any Outer Plane.

Special – All spells are nullified, starting at 9th-level and descending to 0-level, as the caster approaches the Spire. This affects divine magic as well as arcane magic, and cannot be countered with spell keys. The base of the Spire is an anti-magic zone.

Pandemonium

Conjuration – These spells can only summon creatures from the planes of the Abyss, the Astral, Limbo, the Outlands, and Pandemonium. There are spell keys to create any pseudoelemental except fire pseudoelementals.

Divination – The DM secretly makes a Will saving throw for the caster (DC same as spell). If the saving throw is successful, the spell works normally. Otherwise, the caster receives misleading information.

Transmutation – Spells of this school are diminished, and make them look, smell, sound, or feel slightly foul.

Special – Chaotic spells are enhanced; lawful spells are diminished. Wish and limited wish never work on this plane.

Ysgard

Conjuration – Summoning spells call upon einheriar on the first layer, giants or ogres on the second layer, and dwarves or trolls on the third. With a spell key, these spells can only summon creatures from the planes of Arborea, the Astral, Limbo, the Outlands, and Ysgard, with a 1 in 10 chance of failure. Conjuring pseudoelementals is impossible.

Divination – Spells of this school are enhanced, but can only target a single creature. Spells that target locations, mobs, or epic events fail.

Necromancy – Spells of this school use up a spell slot one level higher than its actual level.

Special – Chaotic spells are enhanced; lawful spells are diminished. Weather spells cast by mortals are nullified. Fire spells work without a key in Muspelheim; otherwise, all elemental spells require a runic spell key.