Prototype Portal, Clock of Omens, Grinding Station, and Ancient Den

Prerequisites

• Prototype Portal on the battlefield
• Clock of Omens on the battlefield
• Grinding Station on the battlefield
• Ancient Den in exile

Steps

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

Results

• Infinite landfall triggers
• Infinite tapped land tokens