Tenacious Dead | Ashnod's Altar | Pitiless Plunderer

(and one other card)

Sacrifice
Tenacious Dead to
Ashnod's Altar, generating ({2} magic symbol) .
Pitiless Plunderer,
Mayhem Devil, and
Tenacious Dead trigger; stack the triggers to resolve in that order.
Pitiless Plunderer generates a Treasure token; crack it to float ({B} magic symbol) .
Mayhem Devil triggers again.
Both
Mayhem Devil triggers deals 1 damage each to an opponent for 2 damage.
Resolve the
Tenacious Dead trigger, paying({1} magic symbol) ({B} magic symbol) to return it to the battlefield from the graveyard.
Repeat the sacrifice-recursion loop inflicting damage to opponent infinitely with
Mayhem Devil triggers.