" I don’t get it,” Lex said to Uncle Mort, propelling herself through the air. “Why all these elaborate simulations? And why are the targets so far away from the starting point? When we scythe in to actual targets, they’re always right there in front of us. And time is frozen—and our hoodies protect us from the elements—so why use real fire, real everything?”
“Because the human mind is a tricky little bastard,” Uncle Mort said. “When Grims are thrown into scary situations, their brains still tell them to panic, despite the fact that there is really no need. If the training procedures force you to concentrate on the task at hand while being bombarded with danger from every direction, you’ll be all the more levelheaded when you’re actually in a safe environment.”
“Ah. That makes sense, I guess.”
“Of course it does. I came up with it.”
“With what?”
He gestured at their surroundings. “This.”
“Wait, wait,” said Ferbus. “You designed this?”
“Designed it, no. I don’t know what kind of situations these sadistic Necropolitans have cooked up in the time since I first mentioned it. But it was my idea to establish a training program in the first place.”
“Then why don’t we have one in Croak?” Lex asked.
“We do.” He smirked. “You’re looking at him. "

― Gina Damico , Rogue (Croak, #3)