Gadriel shook his head. "The sorcerer was not in the room. He was in the Warp, reaching through it to corrupt our minds." And it almost worked. This is what he's been trying to tell you!

"I did not know the signs. My brother slew the astropath and the sorcerer revealed himself." And gloated. And mocked them. "Brother Chairon had seen the signs when the Word Bearers attacked Calth."