The Incandescence Light allows editing the incandescence material attributes of one or more objects as light attributes (provided that the object material has support for incandescence). The difference between a mesh light and an incandescence light is that an incandescence light directly controls the incandescence parameter of the geometry's surface shader, preserving the other surface shader properties; a mesh light applies the area light shader on its source mesh instead of its surface shader. One incandescence light can control as many such object/materials as desired.
As with any other light sources, incandescence lights will be listed in the Multi-Light list; each incandescence light can thus be output in its own Multi-Light layer. They also can be edited by 3Delight Display's Mixer.