Panoptic Mirror, and Part the Waterveil

Prerequisites

• Panoptic Mirror on the battlefield
• Part the Waterveil in exile

Steps

1. At the beginning of your upkeep, Panoptic Mirror triggers, casting a copy of Part the Waterveil without paying its mana cost
2. Resolve Part the Waterveil, causing you to take an extra turn after this one
3. Repeat each turn

Results

• Infinite turns