Cunning Rhetoric is a rare Enchantment card from Outlaws of Thunder Junction Commander (OTC), collector number 129. Current market price: $3.56, TCGplayer market prices via Scryfall.
Whenever an opponent attacks you and/or one or more planeswalkers you control, exile the top card of that player's library. You may play that card for as long as it remains exiled, and you may spend mana as though it were mana of any color to cast it.