"Do I?" he asked, clearly amused by the prospect. If the way the tower was reacting to his whims was any indication he didn't exactly believe what this particular Avenger was telling him. He could see right through the ploy- this was just a bid for Captain America to make sure himself that Magnus kept his end of this bargain and spared the people within the tower. Presumably that would mean sparing the tower itself in the end. "And I suppose you'll be that Avenger?"