Reveillark, Activated Sleeper, and Altar of Dementia

Prerequisites

• Reveillark on the battlefield
• Activated Sleeper in the graveyard
• Altar of Dementia on the battlefield

Steps

1. Activate Altar of Dementia by sacrificing Reveillark
2. When Reveillark dies, it triggers, returning Activated Sleeper from your graveyard to the battlefield as a copy of Reveillark
3. Activate Altar of Dementia by sacrificing Activated Sleeper
4. When Activated Sleeper dies, it triggers, returning Activated Sleeper from your graveyard to the battlefield as a copy of Reveillark
5. Resolve the Altar of Dementia ability, causing target player to mill cards equal to Activated Sleeper's power
6. Repeat from step 3

Results

• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite mill
• Infinite sacrifice triggers
• Infinite self-mill