Retreat to Coralhelm + Sakura-Tribe Scout + Arid Archway

Retreat to Coralhelm

Sakura-Tribe Scout

Arid Archway

How it works

1. Activate Sakura-Tribe Scout by tapping it, putting Arid Archway from your hand onto the battlefield.
2. When Arid Archway enters the battlefield, it and Retreat to Coralhelm trigger.
3. Resolve the Arid Archway trigger, returning itself from the battlefield to your hand.
4. Resolve the Retreat to Coralhelm trigger, untapping Sakura-Tribe Scout.
5. Repeat.