Retreat to Coralhelm, Murasa Rootgrazer, and Trench Behemoth

Prerequisites

• Retreat to Coralhelm on the battlefield
• Murasa Rootgrazer on the battlefield
• Trench Behemoth on the battlefield
• You control at least one basic land
• Murasa Rootgrazer 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 Murasa Rootgrazer's first ability by tapping it, putting the basic land from your hand onto the battlefield
4. The land enters the battlefield, triggering Retreat to Coralhelm, untapping Murasa Rootgrazer
5. Repeat

Results

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