Kodama of the East Tree + Oboro, Palace in the Clouds + Springheart Nantuko

Steps

1. Play Oboro, Palace in the Clouds.
2. When Oboro, Palace in the Clouds enters the battlefield, Springheart Nantuko and Kodama of the East Tree trigger.
3. In response, activate Oboro's first ability by tapping it, adding {U}.
4. Activate Oboro's last ability by paying {1}, returning it from the battlefield to your hand.
5. Resolve the Kodama of the East Tree trigger, choosing not to put anything from your hand onto the battlefield.
6. Resolve the Springheart Nantuko trigger, creating a token.
7. When the token enters the battlefield, Kodama of the East Tree triggers, putting Oboro from your hand onto the battlefield.
8. When Oboro, Palace in the Clouds enters the battlefield, Springheart Nantuko triggers.
9. Repeat from step 3.