Tortoise Shell of Open Space (5e Equipment)
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Wondrous item, Very Rare (requires attunement)
This shell, 18 inches in diameter, has a crystal lens embedded in its apex that seems to show a room when looked through.
Demiplane Creation. An attuned creature can use its action to cast the spell Demiplane, but instead of a door appearing, all willing creatures touching the shell are transported into the demiplane, and it always opens to the same demiplane.
Once used this way, this item cannot do so again until the next sunrise.