Spellbinding Soprano + Sprout Swarm + Doubling Season

Spellbinding Soprano

Sprout Swarm

Doubling Season

How it works

1. Activate Spellbinding Soprano's encore ability by paying 3 and exiling it from your graveyard, creating a token copy of it with haste for each opponent you have.
2. Declare each Spellbinding Soprano token as an attacker.
3. Each Spellbinding Soprano token triggers, causing instant and sorcery spells you cast this turn to cost 1 less to cast for each Spellbinding Soprano token.
4. Cast Sprout Swarm with buyback by tapping a green creature and any other creature you control, creating two 1/1 Saproling creature tokens and returning Sprout Swarm to your hand.
5. Repeat step 4.