Obeka, Splitter of Seconds, Smaug the Magnificent, and Time Sieve

Prerequisites

• Obeka, Splitter of Seconds on the battlefield
• Smaug the Magnificent on the battlefield
• Time Sieve on the battlefield

Steps

1. At the beginning of your upkeep, Smaug triggers, creating a Treasure token
2. Deal combat damage using Obeka, triggering its ability, causing you to get at least four extra upkeep steps
3. Repeat step 1 during each extra upkeep step, creating at least four additional Treasures
4. Activate Time Sieve by tapping it and sacrificing five Treasures, causing you to take an extra turn after this one
5. Repeat each turn

Results

• Infinite turns
• Lock