Cavern-Hoard Dragon, and Time Sieve

Prerequisites

• Cavern-Hoard Dragon on the battlefield
• Time Sieve on the battlefield
• An opponent controls at least five artifacts, and cannot block all damage from Cavern-Hoard Dragon, or kill Cavern-Hoard Dragon during combat

Steps

1. Deal combat damage to an opponent using Cavern-Hoard Dragon
2. Cavern-Hoard Dragon triggers, creating a Treasure token for each artifact the opponent controls
3. Activate Time Sieve by tapping it and sacrificing five Treasures, causing you to take an extra turn after this one
4. Repeat each turn as able

Results

• Near-infinite turns