Sprout Swarm with buyback by paying ({G} magic symbol) due to its affinity for creatures, creating a 1/1 Saproling creature token and returning
Sprout Swarm to your hand.
Cast
Sprout Swarm by paying ({0} magic symbol) due to its affinity for creatures and tapping the Saproling, creating a 1/1 Saproling creature token and returning
Sprout Swarm to your hand.
Repeat step 2.
Notes
If you control an untapped green creature as you start, you can tap it in step 1 to reduce