Animate a Forest that enters untapped using Sylvan Awakening
Cast Springheart Nantuko for its bestow cost by paying 1, attaching it to the animated Forest.
Play a land. When the land enters, Springheart Nantuko triggers, causing you to pay 1 to create two token copies of the Forest that enters untapped.
When the Forest tokens enter, Springheart Nantuko triggers twice.
Holding priority, activate the Forest tokens by tapping them, adding .
Resolve the first Springheart Nantuko trigger, choosing not to pay and creating two 1/1 Insect creature tokens.
Resolve the second Springheart Nantuko trigger, causing you to pay 1 to create two token copies of the Forest that enters untapped.
Repeat from step 4.
This delightful loop transforms a humble land drop into an exponentially compounding engine of nature's growth. By animating your lands into creatures using Sylvan Awakening, you create a legal target to bestow Springheart Nantuko onto an active Forest, setting the stage for its landfall ability. Whenever a new land enters the battlefield, the Nantuko triggers to copy its host, but the presence of Primal Vigor supercharges this process by doubling every single token created. This cascade generates infinite tapped Forest tokens, infinite creature tokens, and endless landfall triggers to overwhelm your opponents.