I had 2 Giant Frogs in my hand, and as I drew an Emerald Shield (on it's way from being big in the middle of the screen toward my hand), I played one of them. The Emerald Shield then showed up as a Giant Frog in my hand (but the mouseover image still showed a Emerald Shield.)
When I clicked on it to play it, it took 2 life quanta, and produced a 0/1 creature with "reflect" called Jade Shield, which didn't reduce any incoming damage.