This cloudy white crystal rod has meticulously placed holes bored through it. 
If struck it makes a hollow thud, but when this crystal is within the area of an effect that deals Thunder damage it activates, reverberating with an eerie echo. The triggering effect is duplicated with the crystal at its center and the affected area is considered an extension of the original.
While attuned to this item you automatically succeed on saving throws for any effect that triggers this crystal.