Time Sieve, Myr Battlesphere, and Harnessed Snubhorn

Prerequisites

• Time Sieve on the battlefield
• Myr Battlesphere in the graveyard
• Harnessed Snubhorn on the battlefield

Steps

1. Deal combat damage with Harnessed Snubhorn
2. Harnessed Snubhorn triggers, returning Myr Battlesphere from your graveyard to the battlefield
3. Myr Battlesphere enters the battlefield, creating four 1/1 Myr creature tokens
4. Activate Time Sieve by tapping it, sacrificing Myr Battlesphere and sacrificing the four Myr tokens, causing you to take an extra turn after this one
5. Repeat each turn

Results

• Infinite turns