All creatures, objects, and enchantments within a cube of up to a certain size are transported from the physical realm into an overlapping aetheric realm, or, alternatively, from an aetheric realm into the physical realm. This transfer is permanent, except for unwilling creatures.

Creatures which do not want to remain in that realm and are not native to it get a social save at the start of each of their turns to return to their native realm. (They may choose to fail this save to remain in that realm).

The aetheric realm is a nearly perfect copy of the physical realm, but aetheric elemental storms rage through it. Objects in the aetheric realm and objects in the physical realm appear transparent and ghostly when viewed from the other realm.
Also bear in mind that you may find that you are not alone in the aetheric realm. The aetheric realm is inhabited by elementals and hungry incorporeal creatures.
There is one aetheric realm for each element.

Creatures in the aetheric realm take 1d6 damage of the realm’s element at the end of each of their turns.
Attacks and abilities from the aetheric realm cannot affect creatures in the physical realm.
Attacks and abilities from the physical realm cannot affect creatures in the aetheric realm.
They simply pass through them as if they were not there (because they are not there).
(Attacks and abilities from a creature in a different realm will not affect you, unless it is incorporeal.)
(Attacks and abilities from a creature in the same realm will still affect you.)
Creatures in the aetheric realm are concealed from all senses from creatures in the physical realm.
Creatures in the physical realm are concealed from all senses from creatures in the aetheric realm.
This may be used to hide.
Events that take place in the aetheric realm cannot be scried, except from a place in the aetheric realm aligned to the same element.

Incorporeality:
This spell has a special interaction with incorporeal creatures. Since they exist partly in the physical realm and partly in the aetheric realm at the same time, instead of being swapped between realms, this spell disturbs the magic that lets them shift between the realms, pulling them towards harm. Until they pass a save against this spell, they lose any resistances to damage that they normally have, and if they would normally be immune to a damage type, they only resist it instead.

Reverse Modes:
This spell also has alternative uses. If you are in the aetheric realm, you can cast this spell to transport everything in the area to the physical realm. This is useful information if you do not wish to remain there forever.
You can also use it to pull things in its area from the dimension that you are not in into the dimension that you are in. From either realm, this spell lets you move things from one realm to the other, permanently (unless they don’t want to be there).

Exclusion:
You may try to exclude an object, such as a friendly creature, from being transported between dimensions through a test of spellcraft, or by using Advanced Geometry.

Suggested Backfire: You open a large tear in the wall to the aether dimension, flooding the entire area with hazardous arcane energies which deal 1d6 elemental damage per round to everything in a massive range. Additionally, this tear may suck creatures from the aetheric realm into the physical realm.

Affinity:
When you take this class, choose which elemental aetheric realm your Banish is attuned to.
Whenever you cast this spell, it will normally transport targets to the aetheric realm of that element.
You can try to cast this spell using a different element, but must pass a DC 20 test of Spellcraft each time to change the element from what it normally is.

Move an object, enchantment, or willing creature back to the physical realm.

(If this removes their only source of concealment, they will stop being hidden, but they may still be able to catch the enemy off guard.)
Objects which would appear in the same space as another object are moved nearby.