Planar Transposition
17th-Level Psion Feature
Starting at 17th level, you gain planar transposition the High Science of Psychoportation. This powerful ability allows you to switch a portion of the Prime Material Plane for a portion of another plane. The psionicist may instead transpose a donutshaped ring 10 feet in diameter on the inside and 10 feet wide. The transposed planes remain switched for as long as the psionicist is concentrated.
The exact effects of this power are left to the DM, but some guidelines apply. Inanimate objects can be partially transposed - so a castle may be half in the Prime Material Plane with the psionicist and half in the Elemental Plane of Fire. However, living creatures are either all in or all out. If a creature wanders away from its transposed area into the new surroundings, it doesn't return when the psionicist drops the power.
Note that the psionicist may accidentally transpose an extraplanar creature when he grabs a chunk of its home plane and brings it to The Prime Material Plane. The planes are not interrupted by their transposition; a piece of the Elemental Plane of Fire remains a roaring source of heat, transposing the base of a tower will not cause its top to fall, and so on. However, the new surroundings may affect the transposed areas eventually. A portion of land sent to the Plane of Magma would return a scorched wasteland. Some possibilities with planar transposition include: creating a temporary oasis by transposing bare desert for a piece of the Elemental Plane of Water; opening a passage through a mountain by transposing a portion of the Ethereal Plane; sending a tower filled with enemy soldiers to the Abyss for a time (no telling what'll be in it when the tower comes back... or hiding by surrounding oneself with a donut-shaped area of the Demiplane of Shadow or the Quasielemental Plane of Steam.
Once you use this feature, you can’t use it again until you finish a long rest.
