Twin Vanishing Chests
Wondrous item, very rare (requires attunement by a spellcaster)

These two heavy, rune-carved bed-chests are linked by ancient conjuration magic. When placed on the same plane and ritually attuned (1 hour), they form a paired conduit. Items or creatures placed inside one chest appear in the other at the start of the next round.
Living Transport. A living creature must succeed on a DC 15 Constitution saving throw or take 6d6 force damage. If reduced to 0 hit points, the creature dies instantly.
Fragile Items. Fragile non-magical items (e.g. glass, instruments) must withstand magical stress. Roll +5 to hit against the item’s AC (typically 10–15). On a hit, the item is destroyed. Well-packed items gain +2 AC.
Magic Aura. The chests radiate strong conjuration magic. A DC 18 Arcana check reveals their teleportation function and risks.