Play a land. When the land enters, Springheart Nantuko triggers, causing you to pay 1 to create a token copy of Dryad Arbor.
When the Dryad Arbor token enters, Springheart Nantuko triggers. Holding priority, activate the Dryad Arbor token by tapping it, adding due to Mana Reflection.
Resolve the Springheart Nantuko trigger, causing you to pay 1 to create a token copy of Dryad Arbor.
Repeat from step 2.
This ingenious loop turns a simple land drop into an engine of endless multiplication, anchored by Springheart Nantuko Bestowed onto Dryad Arbor to continuously spawn copies whenever a land enters. As each new Dryad Arbor token arrives, Springheart Nantuko triggers again, allowing you to tap the fresh token for mana to fund the next iteration—a process supercharged by Mana Reflection doubling every generated green into a profusion of surplus mana. Because Dryad Arbor doubles as both land and creature, it seamlessly feeds the landfall chain while Yarus, Roar of the Old Gods waits in the wings to grant haste and leverage your army if you pivot your strategy.