Cayth, Famed Mechanist, and Altar of Dementia

Prerequisites

• Cayth, Famed Mechanist on the battlefield
• Altar of Dementia on the battlefield
• The persist creature does not have a -1/-1 counter on it

Steps

1. Activate Altar of Dementia by sacrificing the persist creature
2. When the persist creature dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
3. When the persist creature enters the battlefield, its fabricate ability triggers, putting a +1/+1 counter on it
4. Resolve the Altar of Dementia ability, causing target player to mill cards equal to the persist creature's power
5. Repeat

Results

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