Raven's Slumber

Raven's Slumber is a magical amulet that belonged to the Champion of the Raven Queen, Purvan Suul. It was recovered from his tomb by Vox Machina and eventually given to Vex'ahlia.

Properties
Raven's Slumber contains some sort of demiplane that can be used to store a living creature indefinitely. This demiplane takes the form of a twenty-square-foot stone room with a throne in the center. On one of the walls is a rectangular window through which the creature contained within can view the outside world from the perspective of the amulet.

When Vox Machina first obtained the amulet it contained Galdric, the wolf companion of Purvan Suul. After the party released him from the amulet, they decided to give it to Vex'ahlia as an easier method of transporting her own companion, Trinket.

If a creature is willing, they can be placed within Raven's Slumber immediately. If they are unwilling, they must succeed a Wisdom saving throw to resist being placed inside.

If Trinket falls unconscious outside of Raven's Slumber but is still within range of it, his unconscious form is instantly transported into the safety of the amulet and stabilized.

If a creature contained within Raven's Slumber attacks the walls with enough force, they can eventually break free and escape, destroying the necklace in the process.

While in the Feywild, Vex'ahlia encountered the gigantic spirit bear Orlan. Trinket defended her, both through fighting and with his words of devotion, and the creature allowed them to go in safety. As its ethereal form passed through them, it imbued Raven's Slumber with a slowly fading blue radiance, allowing Trinket to benefit from Vex's Hunter's Mark and to have an ability called Primal Fury once per short rest to gain advantage on attacks as well as critical attacks on natural rolls of 19 or 20.

Notable Uses
Raven's Slumber is most often used to transport and store Trinket. As a fully grown brown bear, the party had frequently struggled to get him through tight spaces and over obstacles. Once Vex'ahlia was given the amulet, transporting her companion became much easier.

Vex'ahlia used Raven's Slumber to save Grog's life during the battle against Kevdak and the Herd of Storms. Grog had been surrounded by Herd members who were intent on ending his life, but Vex quickly swooped down on her Broom of Flying and placed Grog within the amulet, essentially airlifting him to safety. Soon after that, she released Grog in the air above Kevdak, allowing him to deal the killing blow against his uncle.

While in the Feywild, Vox Machina came upon the campsite of Tsoradun the Happy, which charmed Scanlan and Vax'ildan into dancing uncontrollably around the campfire. Vex used Raven's Slumber on her brother to carry him out of range of the enchanted music.

Trivia

 * The players often refer to Raven's Slumber as a Poké Ball in reference to the Pokémon franchise. Poké Balls are small round capsules used to capture and store the creatures called Pokémon, much like how Vex'ahlia uses Raven's Slumber to carry around Trinket and send him into battle.