[Confused by the unexpected change in subject, Thor tilts his head at Tony's image on the screen and frowns before answering.]

They are quite good. He is a master sorcerer. They have no substance to them, however, and are visual and audible only. That is the true way to determine what is an illusion and what is not.

[He pauses, follows the train of thought to its obvious confusion, and asks,]

Do you have reason to worry about Loki's illusions, Stark?