Prototype Portal, Clock of Omens, Grinding Station, and Great Furnace

Prerequisites

• Prototype Portal on the battlefield
• Clock of Omens on the battlefield
• Grinding Station on the battlefield
• Great Furnace in exile

Steps

1. Activate Prototype Portal by paying and tapping it, creating a token copy of Great Furnace
2. The Great Furnace token enters, triggering Grinding Station, untapping Grinding Station
3. Activate Clock of Omens by tapping the Great Furnace token and Grinding Station, untapping Prototype Portal
4. Repeat

Results

• Infinite landfall triggers
• Infinite tapped land tokens