Altered Bead of Force

Adventuring gear (wondrous item), rare

This small black Sphere measures 3/4 of an inch in diameter and weighs an ounce.

You can use an action to destroy the bead. Each creature within a 15-foot radius of the bead is enclosed by a Sphere of transparent force for 1 minute. Only breathable air can pass through the sphere's wall. No Attack or other effect can, as with the Wall of Force spell.