Tenacious Dead | Altar of Dementia | Pitiless Plunderer

(and one other card)

Activate
Altar of Dementia by sacrificing
Tenacious Dead.
When
Tenacious Dead dies, it triggers itself,
Pitiless Plunderer and
Pawn of Ulamog.
Resolve the
Pitiless Plunderer trigger, creating a Treasure token.
Resolve the
Pawn of Ulamog trigger, creating a 0/1 Eldrazi Spawn creature token.
Resolve the
Altar of Dementia ability, causing target player to mill one card.
Activate the Treasure by tapping and sacrificing it, adding ({B} magic symbol) .
Activate the Eldrazi Spawn by sacrificing it, adding ({C} magic symbol) .
When the Eldrazi Spawn dies,
Pitiless Plunderer triggers, creating a Treasure token.
Resolve
Tenacious Dead's ability from step 2, paying ({1} magic symbol) ({B} magic symbol) to return it from your graveyard to the battlefield tapped.
Repeat any number of times.
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.