Since The Day You Left XVIII: Newborn Quest
The wraiths took to the walls, melting with the shadows of the obsidian. They moved with the grain of the stone, with no one’s noticing them. They were clothed in what seemed to be shadow, as well. The soft black fabric of their suits had no seam, and their contrast with the walls was non-existent as they expertly and silently scaled the thick barricade that stood between them and their targets.
After all, the Yīnyǐng were known to be silent and invisible.