EF_DIMLIGHT
From Valve Developer Community
EF_DIMLIGHT is defined as 0x004, or 4.
This effect creates a dynamic light with an RGB value of 100 100 100 and a random radius of 200 to 231 at the origin.
Usage
To use this effect, turn off SmartEdit mode and add the following keyvalue pair to the entity: effects 4.
Note:If it is desired to use this with other effects, you should add the integer value of each effect to the value.Remember that you can set the effects value during runtime using an entity's AddOutput input with the input value effects x (x being any summation of effects flags to enable).
Warning:Using the AddOutput functionality for this, the new value may interfere with an entity's simulation functionality.