Dour Port-Mage, Temporal Manipulation, and Eternal Witness

Prerequisites

• Dour Port-Mage on the battlefield
• Temporal Manipulation in hand
• Eternal Witness in hand
• available plus enough mana to cast Temporal Manipulation and Eternal Witness each turn

Steps

1. Cast Temporal Manipulation by paying its mana cost, causing you to take an extra turn after this one
2. Cast Eternal Witness by paying its mana cost
3. When Eternal Witness enters the battlefield, it triggers, returning Temporal Manipulation from your graveyard to your hand
4. Move to your next turn
5. Activate Dour Port-Mage by paying and tapping it, returning Eternal Witness from the battlefield to your hand
6. Dour Port-Mage triggers, causing you to draw a card
7. Repeat

Results

• Infinite turns