Activate Kaya's second loyalty ability by removing two loyalty counters from it, causing you to double all tokens you create this turn.
Activate Shilgengar's first ability by sacrificing Falkenrath Forebear,
When Falkenrath Forebear dies, Pitiless Plunderer triggers, creating two Treasure tokens.
Resolve the Shilgengar ability, creating two Blood tokens.
Activate a Treasure by tapping and sacrificing it, adding .
Activate Falkenrath Forebear by paying and sacrificing the two Bloods, returning Falkenrath Forebear from your graveyard to the battlefield.
Repeat from step 2.
This engine relies on Kaya, Geist Hunter’s minus ability to double the artifact tokens you produce, turning a modest sacrifice loop into an explosive cascade. By using Shilgengar, Sire of Famine to sacrifice Falkenrath Forebear, you trigger Pitiless Plunderer to generate a pair of Treasures while Shilgengar churns out double the Blood tokens thanks to Kaya's replacement effect. You can then crack one of those Treasures for black mana to fuel Falkenrath Forebear's self-reanimation ability, looping the process to spin up boundless artifacts, deaths, and mana.