Retreat to Coralhelm, Skyshroud Ranger, and Boros Garrison

Prerequisites

• Retreat to Coralhelm on the battlefield
• Skyshroud Ranger on the battlefield
• Boros Garrison in hand
• Skyshroud Ranger does not have summoning sickness

Steps

1. Activate Skyshroud Ranger by tapping it, putting Boros Garrison from your hand onto the battlefield
2. Boros Garrison enters the battlefield, triggering itself and Retreat to Coralhelm
3. Resolve the Boros Garrison trigger, returning itself from the battlefield to your hand
4. Resolve the Retreat to Coralhelm trigger, untapping Skyshroud Ranger
5. Repeat

Results

• Infinite landfall triggers