The Outermost Portal
Efreet Slave Collar
A slave collar made of hammered copper
These collars, made of hammered copper mined from the Elemental Plane of Earth, are in common use within the City of Brass. Slaves to the Efreeti are often equipped with such magical devices. Most commonly, each collar is keyed magically to a ring with a powerful enchanted gemstone. The wearer of this ring cannot be disobeyed as every word they say is treated for all intents and purposes as a geas spell.
Additionally, the wearer of one of these collars cannot bring themselves to purposefully inflict harm on their masters.