Rod of Security

From Dungeon Master's Guide, page 197. Found on Magic Item Table H.

Description
''Rod, very rare. 2 lbs.''

While holding this rod, you can use an action to activate it. The rod then instantly transports you and up to 199 other willing creatures you can see to a paradise that exists in an extraplanar space. You choose the form that the paradise takes. It could be a tranquil garden, lovely glade, cheery tavern, immense palace, tropical island, fantastic carnival, or whatever else you can imagine. Regardless of its nature, the paradise contains enough water and food to sustain its visitors. Everything else that can be interacted with inside the extraplanar space can exist only there. For example, a flower picked from a garden in the paradise disappears if it is taken outside the extraplanar space.

For each hour spent in the paradise, a visitor regains hit points as if it had spent 1 hit die. Also, creatures don't age while in the paradise, although time passes normally. Visitors can remain in the paradise for up to 200 days divided by the number of creatures present (round down).

When the time runs out or you use an action to end it, all visitors reappear in the location they occupied when you activated the rod, or an unoccupied space nearest that location. The rod can't be used again until ten days have passed.