Stones of Silencing appear as dull silver balls with small grooves on one hemisphere of the sphere. They radiate a grey light for the duration of their activation
The Shadow Thieves are best known for developing and using these items to carry out assassinations in centuries gone past. There were originally only a few dozen created — merely for the assassins within the guild — but since then copycat wizards and spell hurlers have created (and sold) them to adventurers, nobles, and even more dangerous folk.
These items are prized by thieves and assassins and are generally feared most by spell casters. To prevent their own creations from being used against themselves, many wizards have included ways of de-activating one of their Stones of Silencing using somatic gestures. Those gestures are often closely guarded secrets and left unknown to whomever purchases one of these items from the creator.
1/day the owner can cast a Silence spell in a 10 ft. radius from the stone as an action. It lasts for 10 minutes. There is no concentration requirement and the power can be dismissed by the owner as a bonus action.