Koll, the Forgemaster, Deathrender, and Altar of Dementia

Prerequisites

• Koll, the Forgemaster on the battlefield
• Deathrender on the battlefield
• Altar of Dementia on the battlefield
• Deahrender attached to another nontoken creature you control

Steps

1. Activate Altar of Dementia by sacrificing the creature with Deathrender attached
2. When the creature dies, Koll and Deathrender trigger
3. Resolve the Koll trigger, returning the creature from your graveyard to your hand
4. Resolve the Deathrender trigger, putting the creature from your hand onto the battlefield and attaching Deathrender to it
5. Resolve the Altar of Dementia ability from step 1, causing a player to mill cards equal to the creature's power
6. Repeat

Results

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