Dualcaster Mage, Makeshift Mannequin, and Yahenni, Undying Partisan

Prerequisites

• Dualcaster Mage in hand
• Makeshift Mannequin in hand
• Yahenni, Undying Partisan on the battlefield
• available

Steps

1. Cast Makeshift Mannequin by paying its mana cost
2. Holding priority, cast Dualcaster Mage by paying its mana cost
3. When Dualcaster Mage enters, it triggers, targeting Makeshift Mannequin
4. Holding priority, activate Yahenni by sacrificing Dualcaster Mage, Resolve the Dualcaster Mage trigger, copying Makeshift Mannequin Resolve the Makeshift Mannequin copy, returning Dualcaster Mage from your graveyard to the battlefield
5. Repeat from step 3

Results

• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers
• Infinite magecraft triggers