This clever loop locks down the game by taking infinite turns, fueled by recycling key spells through repeated entries and bounces. When you cast Capture of Jingzhou, you secure your extra turn, and then cast Skullwinder to trigger its enter-the-battlefield ability—returning that very same extra turn spell from your graveyard back to your hand so you can cast it again next turn. To keep the engine running smoothly on your subsequent turn, Dour Port-Mage uses its activated ability to bounce Skullwinder safely back to your hand for {1}{U} and a tap. At the same time, the Port-Mage's static triggered ability rewards you with a fresh card draw whenever Skullwinder leaves the battlefield without dying, turning your mechanical loop into a reliable source of card advantage.