Toph, the First Metalbender, Magus of the Candelabra, Thousand-Year Elixir, and Keeper of Progenitus

Prerequisites

• Toph, the First Metalbender on the battlefield
• Magus of the Candelabra on the battlefield
• Thousand-Year Elixir on the battlefield
• Keeper of Progenitus on the battlefield

Steps

1. Activate three in any combination of Mountains, Forests and/or Plains by tapping them, adding
2. Keeper of Progenitus triggers three times, adding
3. Activate Magus of the Candelabra by paying and tapping it, untapping the three mana-producing lands and Thousand-Year Elixir, as it's a land due to Toph
4. Activate Thousand-Year Elixir by paying and tapping it, untapping Magus of the Candelabra
5. Repeat

Results

• Infinite mana lands you control can produce
• Infinite mana nontoken artifacts you control can produce
• Infinite untap of lands you control
• Infinite untap of nontoken artifacts you control