Singing Towers of Darillium [Doctor Who]

Each nonland card in your hand without foretell has foretell. Its foretell cost is equal to its mana cost reduced by 2. (During your turn, you may pay 2 and exile it from your hand face down. Cast it on a later turn for its foretell cost.)
Whenever chaos ensues, you may cast a foretold card you own from exile without paying its mana cost this turn.