Patron of the Moon, Rakdos Carnarium, and Horizon Explorer

Prerequisites

• Patron of the Moon on the battlefield
• Rakdos Carnarium in hand
• Horizon Explorer on the battlefield
• available

Steps

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

Results

• Infinite black mana
• Infinite landfall triggers
• Infinite red mana