Ruli blinked when she pointed out the flaw in Envy's ability to Shadow-Walk, clearly having not realized it before. Envy couldn't see. He could only picture in his head what he already knew. He only knew Ziad. 
And then she mentioned the touch, and he blinked again. That would help. Envy could take mental images, see through another's eye and use it as an escape route. The trust would have to be flawless, though. Zeke, maybe.

"They can, yes." Ruli answered. "If they want, they can tell your body to stop working, and you'll die. But they're not so quick to the chase. They, uh." Ruli sighed, remembering his last little bout with the male Kartaiain in Ziad. "They like to make you relive things. They get into your head quickly and make you feel every bit of paint you've ever felt or inflicted. Every regret. Every fear. They flood your mind with it. Make you feel hollow, ripping everything out and breaking every piece of your body without moving an inch."

He inhaled and sighed. "Envy's never done anything of the sort. At least not since leaving them. He admits that he uses his touch on kids when they come under his supervision. he'll find a favourite food, and favourite game, and use it to build a bond. Only for the tough ones. Like myself." Ruli shrugged. 
"Envy's being blind, it will have to be used to help him. He can take, if offered, a mental image of a location to retreat to. From Zeke, surely, who will have some evacuation plan in mind. Because no. The prisoner ruse won't last long. But, hopefully, by the time it fails, he'll be out of their reach."