Activate Umbral Collar Zealot 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 Umbral Collar Zealot by sacrificing Bloodsoaked Champion.
When Bloodsoaked Champion dies, Pitiless Plunderer triggers, creating a Treasure token.
Resolve the Umbral Collar Zealot abilities from steps 1 and 5
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 clever loop relies on Umbral Collar Zealot as a repeatable sacrifice outlet that simultaneously fuels your graveyard strategy with surveil. Pitiless Plunderer converts each death into a Treasure token to help generate the necessary mana, while Luminous Broodmoth steps in to resurrect the sacrificed creature. However, once Luminous Broodmoth grants that creature a flying counter, its passive ability no longer triggers upon subsequent deaths—which is where Bloodsoaked Champion's own raid ability smoothly takes over to keep the engine running indefinitely.