Pitiless Plunderer trigger, creating a Treasure token.
Resolve the
Pawn of Ulamog trigger, creating a creature token.
Resolve the
Umbral Collar Zealot ability.
Activate the Treasure by tapping and sacrificing it, adding ({B} magic symbol) .
Activate the creature token by sacrificing it, adding ({C} magic symbol) .
When the creature token dies,
Pitiless Plunderer triggers, creating a Treasure token.
Activate the Treasure by tapping and sacrificing it, adding ({R} magic symbol) .
Cast
Squee from your graveyard by paying ({1} magic symbol) ({R} magic symbol) ({R} magic symbol) .
Repeat.
Notes
Once you have infinite Treasure tokens, you may repeat this loop spending mana from Treasures instead of Eldrazi Spawns in step 7, giving you infinite Eldrazi Spawn tokens.