Originally consecrated to the worship of a god of spies and assassins, Telltale Candles allow magical types (ostensibly, the clerics, priests, monks, or nuns of the spy god) to watch the movements and actions of anyone who uses one. Radiating magic if tested for, these will appear as expensive-looking beeswax candles. Each bears what appears to be a candle-maker's stamp on the side or bottom, though in reality, the stamp corresponds to a command word, which can be discovered through some research. Telltale Candles carry a Continual Flame spell upon their wicks which can be turned on or off with this command word. They can therefore burn forever without melting down, nor do they throw off smoke or heat.
It is possible for a worshiper of the god, perhaps secreted in a hidden temple or church, to watch everything that happens under the light of one of these candles, no matter how distant it may be. In such a temple room, ghostly versions of all creatures, places, and things touched by the candle's light will appear before the scrying priest. Note that auditory scrying is not included; the images are silent.
Spy god clerics have these candles created and distributed clandestinely, even giving them away surreptitiously as gifts, so as to spy on sundry important people. Occasionally, these candles fall into the hands of adventurers, who provide welcome entertainment, or even valuable secrets, to the watching clerics.
In darkness Claudia Ramírez Unsplash License modified in Inkscape by David