These creatures communicate wlth each other through changes in color and Intensity. Any human being able to survive in the company of these creatures for an extended period of time might be able to pick up their language, but so far there Is no known case of this. There are reports, however, of drow and similar folk who have the ability to understand the conversations of these terrible monsters.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.