Altar of Dementia, and Railway Brawler

Prerequisites

• Altar of Dementia on the battlefield
• Railway Brawler on the battlefield

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, Railway Brawler triggers, putting a number of +1/+1 counters on the persist creature
4. Resolve the Altar of Dementia ability
5. Repeat

Results

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