Demiplanic orb (5e Equipment)
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Wondrous Item, very rare (requires attunement)
This first appears to be a 5" x 5" glass sphere. Any attuned creature can see a strange mist inside.
Trap If the attuned creature speaks the spheres command word, the mist leeks out of the sphere and darts towards a creature of the character's choice. The chosen creature may make a DC 25 Dexterity saving throw to resist this. If the character fails or is willing, the mist shrinks the target to below diminutive size and sucks it into the glass orb.
While inside the glass orb, the mist creates a demiplane based on the creature's thoughts and will change to the creatures will. Several creatures can be inside the orb at once, and if the attuned creature enters they may still have others enter. If a creature walks to the edge of the sphere, 5,000 feet, they can see out of the orb. If anything is looking at the orb while a creature is at the edge of it, they can see that thing. While a creature is inside the sphere, they may attempt a DC 30 Charisma check. On a success, the creature grows back to normal size and is teleported out of the orb.
Free The attuned creature may speak another command word to free any creature inside the sphere. Any items taken from the orb leave the orb but slowly dissolve into mist over the course of 2d6 minutes.
Fetch If a 3rd command word is spoken (this one is harder to discover) the mist leaves the orb and takes something, or someone, inside the orb out. When it leaves the orb, it's size is small unless the attuned character wants it to be normal sized. If a creature was fetched, and it makes a DC 20 Charisma check, then it is normal sized as well. The creature or object must be returned to the sphere within 4d20 seconds, or the creature/object dissolves into mist and is destroyed. While a creature is outside the sphere in this way, it can use the orb as if it were attuned to it, and it can kill a creature to force that creature into the orb and leave the orb.
Miscellaneous If the orb is shattered, any object in it dissolves into mist and all creatures are released, but their size is diminutive. A creature shrunk in this way may make a DC 30 Charisma check every hour. On a success, they grow one size category until they return to normal.
Any creatures inside the orb don't need anything and don't age. The creature's equipment shrinks and grows with them, and in the case where the creature is out of the sphere, but still shrunk, use reasonable bonuses and penalties.