Hofri Ghostforge, Moorland Rescuer, and Altar of Dementia

Prerequisites

• Hofri Ghostforge on the battlefield
• Moorland Rescuer on the battlefield
• Altar of Dementia on the battlefield

Steps

1. Activate Altar of Dementia by sacrificing Moorland Rescuer
2. Moorland Rescuer dies, triggering itself and Hofri Ghostforge
3. Resolve the Hofri Ghostforge trigger, exiling Moorland Rescuer from your graveyard and creating a token copy of Moorland Rescuer that has "When this creature leaves the battlefield, return the exiled card to your graveyard"
4. Resolve the Moorland Rescuer trigger, returning nothing from your graveyard to the battlefield
5. Resolve the Altar of Dementia ability from step 1, causing target player to mill cards equal to Moorland Rescuer's power
6. Activate Altar of Dementia by sacrificing the Moorland Rescuer token
7. The Moorland Rescuer token dies, triggering itself twice
8. Resolve the Moorland Rescuer token's trigger granted by Hofri Ghostforge, returning Moorland Rescuer from exile to your graveyard
9. Resolve the other Moorland Rescuer trigger, returning Moorland Rescuer from your graveyard to the battlefield
10. Resolve the Altar of Dementia ability from step 6, causing target player to mill cards equal to Moorland Rescuer's power
11. Repeat

Results

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