Armored in his power, he changed his song, reaching out with a shining astral hand to touch the barrier. Motes of light leapt from his fingers to squirm and merge into fragile threads that traced a lattice of energy and revealed the structure of the barrier. The air in the cavern rose to a breeze, then to a wind. It howled forlornly, like a dog bereft of its master. Sam ignored it and concentrated on the pattern.