Yahenni, Undying Partisan | Nether Traitor | Pawn of Ulamog

(and one other card)

Activate
Yahenni by sacrificing
Nether Traitor.
When
Nether Traitor dies,
Pitiless Plunderer and
Pawn of Ulamog trigger.
Resolve the
Pitiless Plunderer trigger, creating a Treasure artifact token.
Resolve the
Pawn of Ulamog trigger, creating a 0/1 Eldrazi Spawn token.
Resolve the
Yahenni ability, giving it indestructible until end of turn.
Activate the Eldrazi Spawn token by sacrificing it, adding ({C} magic symbol) .
When the Eldrazi Spawn dies,
Pitiless Plunderer and
Nether Traitor trigger.
Resolve the
Pitiless Plunderer trigger, creating another Treasure token.
Activate a Treasure token by tapping and sacrificing it, adding ({B} magic symbol) .
Resolve the
Nether Traitor trigger, causing you to pay ({B} magic symbol) to return it from your graveyard to the battlefield.
Repeat.