The precise purpose of this item is unknown. (Actually, the purpose of this item is to quickly introduce new people to the game--in the sense of both "quickly introduce new players to the way D&D works" and "quickly introduce those players' new characters in the middle of a dungeon at the beginning of a session where the original PCs are about to get into a fight with something they ran into at the cliffhanger ending of the last session".)
The cube-shaped (or oblong, or whatever) box is made of glass--2 inches tall on each side--and has gems set into five of the sides.
(Actually, the box is made of clear plastic and the "gems" are sphere-headed pushpins hot-glued onto it.)
The gems, set one to a side, are black, red, green, white, and blue.
(Or whatever color the pushpins you have are.)
Inside the box is a scale model of an existing chamber somewhere in Maleketh's dungeon. (Whatever chamber the original PCs and their foe/foes were about to fight in when the last session ended.)
The real chamber will have an alcove attached to it. (The alcove is where the new PCs wake up.)
Inside the box are tiny and fully-functioning scale replicas of everyone and everything in the chamber.
(Namely, the original PCs and the monster or monsters they were about to fight)
The actions and movements inside the box correspond precisely to whatever is happening inside the chamber.
(Which will be obvious to the newly-arrived PCs because they will wake up with the box lying within reach and they will be able to see out of their alcove and into the replicated chamber through the gaps in a steel grate that separates the chamber from the alcove.)
Touching the gems will cause various events to occur:
Touching the green gem will open or close the grate separating the chamber and the alcove.
(The new PCs will eventually figure out they have a choice about whether to get into the fight immediately.)
Touching the blue gem will move each individual in the chamber(i.e., in the fight) to the position occupied by the next individual in the chamber clockwise from him or her.
(In the right hands, this can be devastating, but more importantly, it'll teach the new PCs something about how combat works.)
Touching the red gem will heal everyone in the chamber for one hit point of damage. This effect only works once every 24 hours.
(This might keep your new PCs from dying immediately. It might also bring the monsters back from the dead if they get knocked unconscious and then somebody starts thinking "Now what does this box do....")
Touching the white gem will turn every living thing in the chamber invisible--and close the steel grate if it's not already closed. (Which might be good for a laugh.)
Touching the black gem will cause a trap door in the ceiling of the alcove to open and cause an unconscious civilian to fall through. (So that's how we ended up here.)
The box and associated chamber may have other secrets as well.
(But that's probably enough to keep them busy for the first session.)