Mortal Mask
A mask brushed with toxic chemicals on the inside that is offered to unsuspected or innocent strangers, who would lose consciousness once they wear it at the request of their evil donors, who would then rob their victims.
At secluded traffic junctions, it’s not uncommon for criminals in police uniforms to stop a car whose driver and fellow passenger are both unmasked, who would be handed a pair of mortal masks to wear before they’re allowed to drive off.