A brilliant radiance; a shining forth.
“Effulgence” strikes me as a great word for that flood of light when the door is opened between a dark chamber and a well-lit one. Maybe the effulgence of light contrasts sharply with the black silhouette of a sinister villain. Or of a Mouser.
Then, from the same direction as the first whistle, came the tread of feed, growing louder. It sounded as if there were only one person, but the effulgence of the light from the door showed that there was also a little man, who walked softly, a little man clad in close-fitting garments of gray — tunic, jerkin, mouseskin cap and cloak.
– Fritz Leiber, “Thieves’ House” (1943)