Ethereal chamber

Ethereal chamber, known as simply chamber by planar travelers,  was a spell used against foes in the ethereal plane. It encapsulated its target in a coccoon of glassy force, trapping them.

Effects
The ethereal chamber spell first needed to be targeted; this required some manner of perception into the ethereal plane (or the caster could simply be there themselves). It created a prison of pure crystalline force around a target that did not vacate its position quickly enough, making it impossible for the entrapped creature to move on the ethereal plane or any of its coterminous planes. Those so encapsulated could still breathe, so it was impossible to suffocate them. It also became impossible for those encased within to make any attacks, though the crystalline force made it difficult to target them as well. The version of the spell that had become most popular by also granted a certain resistance to sonic and gaze attacks to its victims. The version of the spell known before then employed the mists of the ethereal plane instead of force, hardening them into panes of glassy material.

A disintegrate spell would immediately break the effect. Unlike other force spells, sufficient strength could break it, even from the inside, with the level of strength required changing alongside the caster's power. The version of the spell most known before was so strong that even a titan could only break through half the time, though, and no physical damage was enough to break the spell from the outside, as it drew in the mists from the ethereal plane to repair itself.

Components
Besides the verbal component and the somatic component, the spell called for a small piece of translucent glass.

History
The nearly spent Wand of Citrine Force carried by Ususi Manaallin in unleashed an effect almost perfectly matching the spell, except that it operated in the Prime Material plane as well, and that it could be used to create obstacles.