An illusion lantern uses a combination of divination and thought projection to induce intelligent minds in its vicinity to hallucinate what is actually there. The mind must have a concept of sight for this to work, but does not actually need functioning eyes; a blind person can see clearly in the presence of an illusion lantern. This principle can operate even in total darkness, allowing such a device to act as a replacement for light.
The main advantage of an illusion lantern is that it does not use any physical energy, and can therefore remain in continuous operation for thousands of years. Many other magical light sources, such as arc lanterns and magma lanterns, do not run out of energy since their power is summoned, but can still be damaged by thermal stress during prolonged operation.
The "light" from an illusion lantern is not the same as physical light, which can lead to a number of idiosyncratic effects. One is the lack of shadows from an illusion lantern. Objects will still appear to have shading, because that is how the mind is used to perceiving three-dimensional objects, but the actual direction of the light source will be ambiguous. Another is the abrupt transition between the illuminated and non-illuminated space; objects out of the range of the illusion lantern are shrouded in total darkness as if they did not exist, and a person entering the illusion lantern's range will perceive things as if the light were suddenly turned on. In addition, some cheap illusion lanterns lack color perception; a person within its range will see things as if they were suddenly plunged into a black-and-white movie.
Illusion lanterns were commonly used by the Gomla civilization. This is partly because of their extensive use of underground spaces, which would be difficult to illuminate any other way, and partly because of their expertise in thought projection magic. Most extant illusion lanterns are artifacts from that civilization.