Iron Flask

Wondrous Item, Legendary

While holding this brass-stoppered iron flask, you can take a Magic action to target a creature you can see within 60 feet. If the flask is empty and the target is native to a different plane of existence than the one you’re on, it must succeed on a DC 17 Wisdom saving throw or be trapped inside the flask. If the creature has previously been trapped by the flask, it has Advantage on the saving throw.

A trapped creature remains in the flask until released. It doesn’t age and doesn’t need to breathe, eat, or drink while inside. The flask can hold only one creature at a time.

You can take a Magic action to remove the flask’s stopper and release the creature. Upon release, the creature obeys your commands for 1 hour, understanding your commands even if it doesn’t know your language. If you issue no commands, or issue commands that would result in its death or imprisonment, the creature defends itself but takes no other actions. After 1 hour, it reverts to its normal disposition and alignment.

Casting Identify on the flask reveals if a creature is trapped inside, but the type of creature can only be determined by opening the flask. A newly found Iron Flask might already contain a creature, determined by the GM.