Dour Port-Mage + Vampire Charmseeker + Capture of Jingzhou

Dour Port-Mage

Vampire Charmseeker

Capture of Jingzhou

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 Vampire Charmseeker by paying its mana cost.
3. When Vampire Charmseeker 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 Vampire Charmseeker from the battlefield to your hand.
6. Dour Port-Mage triggers, causing you to draw a card.
7. Repeat.

This clever loop achieves infinite turns by recycling Capture of Jingzhou over and over with Vampire Charmseeker, which enters the battlefield to pull the extra-turn spell right back out of your graveyard. To keep the engine running, Dour Port-Mage steps in with its activated ability to bounce Vampire Charmseeker back to your hand, allowing you to recast it repeatedly. Meanwhile, Dour Port-Mage's passive triggered ability rewards this bouncing by drawing you a card every time the Charmseeker leaves the battlefield without dying, turning your infinite turn lock into a fully stocked hand as well.