Battle Screech

You can tap any untapped white creatures you control to pay for Battle Screech’s flashback cost, even ones you haven’t controlled continuously since the beginning of your most recent turn.

If a card with flashback is put into your graveyard during your turn, you can cast it if it's legal to do so before any other player can take any actions.

“Flashback [cost]” means “You may cast this card from your graveyard by paying [cost] rather than paying its mana cost” and “If the flashback cost was paid, exile this card instead of putting it anywhere else any time it would leave the stack.”