Tenacious Dead | Pitiless Plunderer | Blasting Station (and one other card)

Cards

Activate
Blasting Station by tapping it and sacrificing
Tenacious Dead.
When
Tenacious Dead dies, it,
Sifter of Skulls, and
Pitiless Plunderer trigger.
Resolve the
Pitiless Plunderer trigger, creating a Treasure token.
Resolve the
Sifter of Skulls trigger, creating a creature token.
When the token enters,
Blasting Station triggers, untapping itself.
In response to the remaining trigger, activate
Blasting Station by tapping it and sacrificing the creature token.
When the creature token dies,
Pitiless Plunderer triggers, creating a Treasure token.
Resolve the
Blasting Station ability from step 6.
Activate two Treasure tokens by tapping and sacrificing them, adding ({B} magic symbol) ({B} magic symbol) .
Resolve the
Tenacious Dead trigger, paying ({1} magic symbol) ({B} magic symbol) to return it to the battlefield from your graveyard.
When
Tenacious Dead enters,
Blasting Station triggers, untapping itself.
Resolve the
Blasting Station ability from step 1.
Repeat.

This combo has been estimated to be Exhibition (Bracket 1+).