Cast Notorious Throng for its prowl cost by paying 5, causing you to take an extra turn after this one.
Cast Skullwinder by paying its mana cost.
When Skullwinder enters the battlefield, it triggers, returning Notorious Throng from your graveyard to your hand.
Move to your next turn.
Activate Dour Port-Mage by paying 1 and tapping it, returning Skullwinder from the battlefield to your hand.
Dour Port-Mage triggers, causing you to draw a card.
Repeat.
This clever loop harnesses the recursive power of Skullwinder to endlessly retrieve Notorious Throng from your graveyard, casting it each turn by meeting its prowl condition to secure infinite turns. Meanwhile, Dour Port-Mage plays a dual role: its activated ability conveniently bounces Skullwinder back to your hand for recast, while its passive triggered ability rewards that departure by drawing you a card every single loop.