原文Scout's Warning allows you to cast a noncreature card with morph (such as Lumithread Field) face down as though it had flash. It won't affect that card if you cast it face up.
原文You don't choose a creature card when Scout's Warning resolves. Rather, this sets up a rule that is true for you until the turn ends or until you cast a creature card, even if you cast that creature at a time you normally could.
原文After Scout's Warning resolves, you can suspend a creature card in your hand any time you can cast an instant. As soon as you actually cast a creature card, you lose this capability.