Mazzy, Truesword Paladin, Phyrexian Altar, and Historian's Boon

Prerequisites

• Mazzy, Truesword Paladin on the battlefield
• Phyrexian Altar on the battlefield
• Historian's Boon on the battlefield

Steps

1. Activate Phyrexian Altar by sacrificing the creature with the Aura attached, adding one mana of any color
2. Mazzy's second ability triggers, exiling the Aura and allowing you to cast it until your next turn
3. Cast the Aura from exile by paying its mana cost, attaching it to any other creature you control
4. When the Aura enters, Historian's Boon triggers, creating a creature token
5. Repeat

Results

• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite sacrifice triggers
• Infinite storm count