Resolve the Soul of Windgrace trigger, returning a land card from your graveyard to the battlefield tapped.
Move to your postcombat main phase.
Cast Waves of Aggression from your graveyard for its retrace cost by paying ({3} magic symbol) ({R} magic symbol) ({R} magic symbol) and discarding a land card, causing you to untap all creatures that attacked this turn, and to get an additional combat and main phase after this one.