Time Sieve, Encroaching Mycosynth, Helm of the Host, and Avenger of Zendikar

Prerequisites

• Time Sieve on the battlefield
• Encroaching Mycosynth on the battlefield
• Helm of the Host on the battlefield
• Avenger of Zendikar on the battlefield
• Helm of the Host attached to Avenger of Zendikar
• You control at least four lands

Steps

1. At the beginning of your combat phase, Helm of the Host triggers, creating a token copy of Avenger of Zendikar with haste
2. When the Avenger of Zendikar token enters the battlefield, it triggers, creating a 0/1 Plant creature token for each land you control
3. Activate Time Sieve by tapping it and sacrificing five creature tokens, causing you to take an extra turn after this one
4. Repeat each turn

Results

• Infinite turns