Book of Vile Darkness 3.5
By Monte Cook
The wearer of this iron ring, emblazoned with the symbol of a brooding falcon, can deal 3d6 points of damage per round as a free action to anyone wearing a slave ring keyed to it. Furthermore, the wearer can exchange messages with anyone wearing a slave ring (as if using a sending spell) three times per day. Typically, a master ring has ten slave rings keyed to it.