Astral Reliquary

This small, ornate box is adorned with shimmering constellations and contains a hidden pocket dimension within. The Reliquary can store up to 50 pounds, but the stored items cannot exceed 1 cubic foot in volume each. To store or retrieve an item, the user must hold the box and speak the command word while envisioning the object. The item will either vanish into or emerge from the pocket dimension. Unlike a standard Bag of Holding, this box is tethered to the Astral Plane. If the box is ever destroyed, its contents remain suspended in the Astral Plane and may be recovered by a powerful mage or planar traveler.  The box can be locked with a second command word, making it invisible to divination magic unless detected from the Astral Plane or by creatures with truesight. Once per long rest, the user can use the box to phase themselves into the Astral Plane, as if affected by the Etherealness spell, for up to one minute before snapping back to the Material Plane.