One of your pieces (your king excepted) becomes delightfully plush for the rest of the game (purely decorative) and cannot be captured for your opponent's next 2 turns.
You draft Rubber Duck in either mode. Activated: you choose when to use it, and using it is your move for that turn.
As a item card, it is a one-use consumable, drafted in either mode.
“Explain your plan to it. It already knows the refutation.”