Athreos, Shroud-Veiled, Denry Klin, Editor in Chief, and Altar of Dementia

Prerequisites

• Athreos, Shroud-Veiled on the battlefield
• Denry Klin, Editor in Chief on the battlefield
• Altar of Dementia on the battlefield
• Denry Klin and another nontoken creature you control each have a coin counter on them

Steps

1. Activate Altar of Dementia by sacrifiing another nontoken creature with a coin counter on it
2. When the creature dies, Athreos' third ability triggers, returning the creature from your graveyard to the battlefield
3. When the creature enters the battlefield, Denry Klin triggers, putting a coin counter on it
4. Resolve the Altar of Dementia ability from step 1, causing target player to mill cards equal to the sacrificed creature's power
5. Repeat

Results

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