Taken from entities.def:
//=============================================================================
/*QUAKED misc_light_flare (.65 .65 1) (-8 -8 -8) (8 8 8) SPAWN_DISABLED
A light flare entity.
-------- KEYS --------
targetShaderName: The name of the shader of the light flare.
radius: The radius key is a vector.
The first component is the size of the light flare. The radius is calculated by taking the distance of the viewer from the light flare and dividing by this key, so the larger the key value, the smaller the flare. Values between 2 and 10 are sensible.
The second component indicates the angle around the direction the flare points for which it is visible. For example a value of 90 means that you can see the flare while infront of the entity, but not when behind it. If set to zero the light flare will be visible from any angle
The third component is similar to the first except that it specifies the size of the light source rather than the size of the light flare itself. This is useful when the higher detail flare fading modes are enabled. If this is set to the same value as the first component, fading will commence as soon as the edge of the light flare is occluded by some surface between the viewer and the flare. If it is set larger the flare will overlap the occluding surface before it begins to fade.
angles: This reflects which direction the flare points. It is not important unless the second component of the radius key is employed. angles is a vector of PITCH YAW ROLL. For example a value of "90 0 0" would create a flare pointing down. ROLL is redundant in this context and can be set arbitrarily.
-------- SPAWNFLAGS --------
SPAWN_DISABLED: Spawn disabled.
-------- NOTES --------
Triggering this entity toggles it.
*/