Mortuary, Gray Merchant of Asphodel, Altar of Dementia, and Bolas's Citadel

Prerequisites

• Mortuary on the battlefield
• Gray Merchant of Asphodel in hand or in the library
• Altar of Dementia on the battlefield
• Bolas's Citadel on the battlefield

Steps

1. Cast Gray Merchant either from your hand by paying or from the top of your library by paying 5 life
2. When Gray Merchant enters, it triggers, causing each opponent to lose life equal to your devotion to black and causing you to gain life equal to the life lost this way
3. Activate Altar of Dementia by sacrificing Gray Merchant
4. When Gray Merchant dies, Mortuary triggers, putting Gray Merchant from your graveyard onto the top of your library
5. Resolve the Altar of Dementia ability
6. Repeat

Results

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