Dour Port-Mage + Capture of Jingzhou + Possessed Skaab

Dour Port-Mage

Capture of Jingzhou

Possessed Skaab

How it works

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

This engine achieves infinite turns by recycling Capture of Jingzhou indefinitely with the help of Possessed Skaab, which fishes the extra-turn spell right back out of your graveyard the moment it enters the battlefield. Meanwhile, Dour Port-Mage plays a double role: its activated ability bounces the Skaab back to your hand so you can replay it on subsequent turns, and its passive triggered ability rewards all this perpetual motion by drawing you a card every single time the Skaab leaves the battlefield without dying.