Retreat to Coralhelm + Cloudstone Curio + Llanowar Scout

Retreat to Coralhelm

Cloudstone Curio

Llanowar Scout

How it works

1. Activate Llanowar Scout by tapping it, putting a nonartifact land from your hand onto the battlefield.
2. When the land enters the battlefield, Retreat to Coralhelm and Cloudstone Curio trigger.
3. Resolve the Retreat to Coralhelm trigger, untapping Llanowar Scout.
4. Resolve the Cloudstone Curio trigger, returning any other nonartifact land from the battlefield to your hand.
5. If the land entered untapped and can produce mana, you may activate it by tapping it, adding at least 1.
6. Repeat.