Soul of Windgrace + Waves of Aggression + Klauth, Unrivaled Ancient + Boros Garrison
Soul of Windgrace
Waves of Aggression
Klauth, Unrivaled Ancient
Boros Garrison
Infinite combat phasesInfinite landfall triggersInfinite magecraft triggersInfinite self-discard triggersInfinite storm countInfinite untap of most creatures you controlInfinite colored mana
How it works
Declare Klauth and Soul of Windgrace as attackers.
When they attack, Klauth and Soul of Windgrace trigger.
Resolve the Klauth trigger, adding at least nine mana that you will not lose this turn as steps and phases end.
Resolve the Soul of Windgrace trigger, returning Boros Garrison from your graveyard to the battlefield tapped.
When Boros Garrison enters, it triggers, returning itself from the battlefield to your hand.
In your next main phase, cast Waves of Aggression from your graveyard for its retrace cost by paying 3R/WR/W and discarding Boros Garrison, causing you to untap all creatures that attacked this turn, and to get an additional combat and main phase after this one.