The Desolation is one of The Entities. It is also known as "The Lightless Flame." It is a manifestation of the fear of pain, of loss, burning, fear of unthinking or cruel destruction: "all of the worst parts of fire, with none of the warmth". Jude Perry calls it "a reckoning, a surging tide of destruction and pain" and "blackened earth, the destructive agonizing heat of burning flesh and land scoured of life, the light with the comfort of fire stripped from it, leaving nothing but the terror of its approach." (MAG 89)
The Cult of the Lightless Flame is an organisation that seems to be aligned to it. Cult members are enriched by destroying the lives of people who had things to live for, destroying things before their potential is realized. In exchange, the cult members can create heat--but not fire--and gain the ability to make their skin run like wax.