Lost in the Underdark I

"To Dinin’s superior eyes, which translated subtle variations of heat into vivid and colorful images, the Underdark was far from a lightless place. Colors all across the spectrum swirled before him in the stone of the walls and the floor, heated by some distant fissure or hot stream. The heat of living things was the most distinctive, letting the dark elf view his enemies in details as intricate as any surface dweller would find in brilliant daylight."