Activate Tortured Existence by paying and discarding a creature card, returning another creature card from your graveyard to your hand.
Teval triggers, creating a creature token.
Activate Umbral Collar Zealot by sacrificing the creature token.
When the creature token dies, Pitiless Plunderer triggers, creating a Treasure token.
Resolve the Umbral Collar Zealot ability.
Activate a Treasure by tapping and sacrificing it, adding .
Repeat.
This ingenious engine turns a quiet graveyard cycle into a relentless procession of the undead, fueled entirely by recycling and sacrifice. You start by activating Tortured Existence to swap a creature in your hand with one in your graveyard, which immediately feeds Teval, the Balanced Scale to birth a fresh Zombie Druid token. You can then feed that token to Umbral Collar Zealot, whose sacrifice trigger lets you surveil while simultaneously tripping Pitiless Plunderer to generate a shiny Treasure token. Cracking that Treasure yields the black mana needed to feed Tortured Existence all over again, keeping the loop spinning forever.