Altar of Dementia, River Kelpie, and Thran Vigil

Prerequisites

• Altar of Dementia on the battlefield
• River Kelpie on the battlefield
• Thran Vigil on the battlefield

Steps

1. Activate Altar of Dementia by sacrificing River Kelpie
2. When River Kelpie dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
3. Thran Vigil and River Kelpie trigger
4. Resolve the Thran Vigil trigger, putting a +1/+1 counter on River Kelpie
5. Resolve the River Kelpie trigger, causing you to draw a card
6. Resolve the Altar of Dementia ability Repeat

Results

• Infinite card draw
• Infinite draw triggers
• Infinite mill
• Near-infinite ETB
• Near-infinite LTB
• Near-infinite death triggers
• Near-infinite mill
• Near-infinite sacrifice triggers