Time Sieve, Encroaching Mycosynth, Helm of the Host, and Lena, Selfless Champion

Prerequisites

• Time Sieve on the battlefield
• Encroaching Mycosynth on the battlefield
• Helm of the Host on the battlefield
• Lena, Selfless Champion on the battlefield
• Helm of the Host attached to Lena
• You control at least four nontoken creatures

Steps

1. At the beginning of your combat phase, Helm of the Host triggers, creating a nonlegendary token copy of Lena with haste
2. When the Lena token enters the battlefield, it triggers, creating a number of 1/1 Soldier creature tokens equal to the number of nontoken creatures 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