Eldritch Confinement

A haunting incantation spoken in the shadows, Eldritch Confinement calls upon the arcane forces to manifest an immobile, crystalline prison in the form of a cube at a point of your choosing within range. The dimensions of the prison are under the caster's control, ranging from a diminutive bottle to a spacious room, adapting to the whims of the sorcerer.

Special Condition: Eldritch Confinement can only be cast on creatures that have been critically wounded, their life force teetering at the brink (reduced to 5% of their maximum hit points).

When the spell is cast, a single creature touched by the caster becomes ensnared within the confines of the crystalline structure. For creatures too large to fully fit, a constitution saving throw is compelled. Success results in a forceful expulsion from the central area, while failure subjects the creature to an inexorable pull into the ethereal prison.

The crystalline barrier, impervious to the passage of matter, also disrupts the flow of magical energies. Attempts to cast spells into or out of the prison are thwarted, and the very act of trying to escape through teleportation or interplanar travel invokes a siphoning effect. The spell's mana is drained, feeding into the containment runes and reinforcing the prison's magical bonds.

Notably, Eldritch Confinement extends its influence into the Ethereal Plane, rendering ethereal travel ineffectual for those within its grasp. This dual-plane warding adds an extra layer of security to the prison.