Sifter of Skulls

Pawn of Ulamog wearing a bigger body. The death-into-token effect first showed up in black on a five-mana, smaller frame; this is the four-mana revision that trades a point of toughness on the original's shell for a 4/3 that actually contributes to a board. The Scion it makes carries the Eldrazi clause that separates this engine from a straight token generator: each one sacrifices for colorless mana, so the deaths you are already accumulating become ramp, and the ramp can power the colorless spells that sit at the top of an Eldrazi curve. The nontoken restriction is the discipline that keeps the loop from going infinite: the Scions it spawns cannot themselves feed it, so a sacrifice outlet plus this card converts your real creatures into bodies and mana exactly once each, not forever. Devoid is doing quiet work too, making the whole package colorless on the stack and in the graveyard even though it costs black mana to cast, which matters anywhere "colorless creature" is a condition rather than a flavor note. What this asks of a deck, then, is that the dying was already happening: it does not start an aristocrats engine, it taxes one for the additional dimension of colorless mana, and it pays for itself only as fast as your own creatures are willing to fall.