Infinite Reflection attached to Brandywine Farmer.
You control a Food.
Steps
Activate Cauldron Familiar by sacrificing a Food, returning it to the battlefield from your graveyard as a copy of Brandywine Farmer due to Infinite Reflection.
When Cauldron Familiar enters the battlefield, it triggers, creating a Food artifact token.
Activate Altar of Dementia by sacrificing Cauldron Familiar.
When Cauldron Familiar dies, it triggers, creating a Food artifact token.
Resolve the Altar of Dementia ability, causing target player to mill cards equal to Cauldron Familiar's power.
Repeat for infinite Food tokens.
Activate Altar of Dementia by sacrificing Brandywine Farmer.
When Brandywine Farmer dies, it triggers, creating a Food artifact token.
Resolve the Altar of Dementia ability, causing target player to mill cards equal to Brandywine Farmer's power.
Activate Cauldron Familiar by sacrificing a Food, returning it to the battlefield from your graveyard.
When Cauldron Familiar enters the battlefield, it triggers, causing each opponent to lose 1 life and you to gain one life.
Activate Altar of Dementia by sacrificing Cauldron Familiar, causing target player to mill cards equal to Cauldron Familiar's power.