Aurelia, the Warleader, Adarkar Valkyrie, and Altar of Dementia

Prerequisites

• Aurelia, the Warleader on the battlefield
• Adarkar Valkyrie on the battlefield
• Altar of Dementia on the battlefield

Steps

1. Declare Aurelia as an attacker
2. Aurelia triggers, causing you to untap all creatures you control and to get an additional combat phase after this one
3. Holding priority, activate Adarkar Valkyrie by tapping it, making it so the next time Aurelia dies this turn it will be returned to the battlefield
4. Activate Altar of Dementia by sacrificing Aurelia
5. Adarkar Valkyrie triggers, returning Aurelia to the battlefield
6. Resolve the Altar of Dementia's ability, causing target player to mill cards equal to Aurelia's power
7. Repeat

Results

• Infinite combat phases
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite mill
• Infinite sacrifice triggers
• Infinite untaps of creatures you control