Winged Words

• WWizards of the Coast2019-07-12
  Official Ruling
  Once you announce that you're casting Winged Words, no player may take actions until the spell has been paid for. Notably, opponents can't try to change whether you control a creature with flying.
• WWizards of the Coast2019-07-12
  Official Ruling
  Winged Words costs only less to cast if you control multiple creatures with flying.

Rulings via Scryfall