Patron of the Moon, Gruul Turf, and Horizon Explorer

Prerequisites

• Patron of the Moon on the battlefield
• Gruul Turf in hand
• Horizon Explorer on the battlefield
• available

Steps

1. Pay to activate Patron of the Moon, putting Gruul Turf from your hand onto the battlefield untapped due to Horizon Explorer
2. When Gruul Turf enters, it triggers
3. Activate Gruul Turf by tapping it, adding two mana
4. Resolve Gruul Turf's triggered ability, returning it from the battlefield to your hand
5. Repeat

Results

• Infinite green mana
• Infinite landfall triggers
• Infinite red mana