Agatha's Soul Cauldron, Siren of the Silent Song, and North Pole Patrol

Prerequisites

• Agatha's Soul Cauldron on the battlefield
• Siren of the Silent Song on the battlefield
• North Pole Patrol in exile

Steps

1. Activate Siren of the Silent Song using North Pole Patrol's ability by tapping it, untapping another creature you control that has a +1/+1 counter on it
2. Activate the other creature using North Pole Patrol's ability by tapping it, untapping Siren of the Silent Song Siren of the Silent Song triggers, causing each opponent to discard and mill a card
3. Repeat

Results

• Infinite mill