Retreat to Coralhelm, Skyshroud Ranger, and Dimir Aqueduct

Prerequisites

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

Steps

1. Activate Skyshroud Ranger by tapping it, putting Dimir Aqueduct from your hand onto the battlefield
2. Dimir Aqueduct enters the battlefield, triggering itself and Retreat to Coralhelm
3. Resolve the Dimir Aqueduct 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