Infernal puzzle box

An infernal puzzle box was a magical item used to protect small objects.

Description
They made from connected material sourced from the Nine Hells, often infernal iron. They were also found crafted from bone. Each side of the box was usually about wide.

Powers
Their most common use was to protect contracts signed between a devil and a mortal creature. They could also be used to safeguard small items. When an item was placed inside the box, it sealed itself automatically, creating a magical seal which was impenetrable. This magical seal also gave the box immunity to all damage. The weight of the box never changed, no matter how heavy an object place inside it was. Once sealed, the only way to open a box was to successfully solve its puzzle. Each boxes puzzle was unique and could only be solved without using magical abilities or spells. If a creature failed to solve the puzzle, they were struck by a painful psychic-based attack.

Appearances

 * Adventures
 * Baldur's Gate: Descent into Avernus