How can you create a combo with Retreat to Coralhelm, Murasa Rootgrazer, Trench Behemoth?
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[START OF COMBO]This combo can be formed with Retreat to Coralhelm, Murasa Rootgrazer, Trench Behemoth

Color identity: GWU
Mana cost: 
Steps:
  1. Activate a basic land you control by tapping it, adding at least {1}.
  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.[END OF COMBO STEPS]

Result:
  - Infinite landfall triggers
  - Infinite mana basic lands you control can produce[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - All permanants must be on the battlefield
  - You control at least one basic land.
  - Murasa Rootgrazer does not have summoning sickness.
[END OF COMBO PREREQUISITES]
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