Vader looked down at himself (what was left of himself) and then back at Luke. His mouth couldn't be seen which was just a well, because his mouth was twisted into something that might have once been a smirk. "Do you believe it would do something being roasted alive would not? Or do you believe I lack the knowledge in the Force to undo your efforts?"

Luke opened the door with questions. But it should be noted: personification of nightmares or not, he's not done anything but (temporary) steal Luke's papers and mock him a bit.