Activate Altar of Dementia by sacrificing Bloodsoaked Champion.
When Bloodsoaked Champion dies, Luminous Broodmoth and Pitiless Plunderer trigger.
Resolve the Luminous Broodmoth trigger, returning Bloodsoaked Champion from your graveyard to the battlefield with a flying counter on it.
Resolve the Pitiless Plunderer trigger, creating a Treasure token.
Activate Altar of Dementia by sacrificing Bloodsoaked Champion.
When Bloodsoaked Champion dies, Pitiless Plunderer triggers, creating a Treasure token.
Resolve the Altar of Dementia abilities from steps 1 and 5, causing target player to mill cards equal to twice Bloodsoaked Champion's power.
Activate the Treasures by tapping and sacrificing them, adding 1.
Activate Bloodsoaked Champion by paying 1, returning it from your graveyard to the battlefield.
Repeat.
This intricate loop transforms a humble recursive threat into an unstoppable engine by leveraging Luminous Broodmoth to bypass traditional graveyard restrictions through the granting of a flying counter. Pitiless Plunderer converts each sacrifice into the necessary mana, fueling both future loops and Altar of Dementia's relentless milling power. The first iteration uses the Broodmoth's resurrection trigger, but once Bloodsoaked Champion acquires that flying counter, subsequent loops instead rely on the Champion's own raid ability paid for by the generated Treasures.