Valkyrie of the Seven Swans

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)

When Valkyrie of the Seven Swans enters the battlefield, create Svanhild, a legendary 1/3 blue Angel creature token with hexproof and seven 2/2 blue Bird creature tokens with flying. Birds you control can't attack for as long as you control Svanhild and can't block for as long as you control Valkyrie of the Seven Swans.

{1}{u}, exile a Bird: Draw a card.