Rare Wondrous Item (Emerald)

You can use your action to choose a familiar location, using the same mechanics and chances as if you were choosing a destination via the Teleport spell, and a 5-foot diameter closed green portal appears in an unoccupied space of your choosing within 30 feet.
At the end of your next turn, the portal will open and will remain open until the end of your next subsequent turn.
Any creature or object  that moves through the portal will be teleported to the destination as if they were the target of your Teleport spell.