Retreat to Coralhelm, Skyshroud Ranger, and Trench Behemoth

Prerequisites

• Retreat to Coralhelm on the battlefield
• Skyshroud Ranger on the battlefield
• Trench Behemoth on the battlefield
• You control at least one basic land
• Skyshroud Ranger does not have summoning sickness

Steps

1. Activate a basic land you control by tapping it, adding at least
2. Activate Trench Behemoth by returning the basic land from the battlefield to your hand, untapping Trench Behemoth
3. Activate Skyshroud Ranger by tapping it, putting the basic land from your hand onto the battlefield
4. The land enters the battlefield, triggering Retreat to Coralhelm, untapping Skyshroud Ranger
5. Repeat

Results

• Infinite landfall triggers
• Infinite mana basic lands you control can produce