"You know magic can do terrible, HORRIFIC things to a person, living or dead."
"Or, it can do really GOOD things, like bringing the dead back to life, and healing wounds. You'd like that wouldn't you."
"If you tell us what we need to know, we can use the GOOD magic, otherwise I'm afraid our only recourse will be to use the OTHER kind. You understand that's the choice is in your hands, right?"