Conduit of Worlds, Time Stretch, Shipwreck Dowser, and Phyrexian Altar

Prerequisites

• Conduit of Worlds on the battlefield
• Time Stretch in hand
• Shipwreck Dowser on the battlefield
• Phyrexian Altar on the battlefield
• each odd-numbered turn, with available each even-numbered turn available

Steps

1. Activate Phyrexian Altar by sacrificing Shipwreck Dowser, adding
2. Cast Time Stretch by paying , causing you to take two extra turns after this one
3. Move to your first extra turn
4. Activate Conduit of Worlds by tapping it, causing you to pay to cast Shipwreck Dowser from your graveyard
5. When Shipwreck Dowser enters the battlefield, it triggers, returning Time Stretch from your graveyard to your hand
6. Move to your second extra turn
7. Repeat

Results

• Infinite turns