Toph, the First Metalbender, Bumi, Unleashed, and Biotransference

Prerequisites

• Toph, the First Metalbender on the battlefield
• Bumi, Unleashed on the battlefield
• Biotransference on the battlefield

Steps

1. Deal combat damage to an opponent
2. Bumi triggers, untapping all lands you control, including Bumi as it's a land due to Toph, and causing you to get an additional combat phase after this one
3. Repeat each combat phase

Results

• Infinite combat phases
• Infinite mana lands you control can produce
• Infinite combat damage