Release to the Wind

• WWizards of the Coast2018-01-19
  Official Ruling
  If an exiled card has in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.
• WWizards of the Coast2018-01-19
  Official Ruling
  Casting the exiled card follows the normal timing rules for casting that card. For example, if the card is a creature card, you can cast that card only during your main phase while the stack is empty.
• WWizards of the Coast2018-01-19
  Official Ruling
  If you cast a card “without paying its mana cost,” you can’t pay any alternative costs. You can, however, pay additional costs. If the card has any mandatory additional costs, such as that of Silvergill Adept, those must be paid to cast the card.
• WWizards of the Coast2018-01-19
  Official Ruling
  If a token is exiled this way, it can’t be cast.

Rulings via Scryfall