Oboro Breezecaller + Retreat to Coralhelm + Skyshroud Ranger

Oboro Breezecaller

Retreat to Coralhelm

Skyshroud Ranger

How it works

1. Activate Skyshroud Ranger by tapping it, putting a land from your hand onto the battlefield.
2. When the land enters the battlefield, Retreat to Coralhelm triggers, untapping Skyshroud Ranger.
3. Activate the land and another land by tapping them, adding at least 2.
4. Activate Oboro Breezecaller by paying 2 and returning a land from the battlefield to your hand, untapping another land.
5. Repeat.