Worm Harvest

The retrace text is the whole machine here: most cards spend their graveyard once, but this one feeds on the same resource twice. The token count scales off lands in your graveyard, and retrace lets you recast it by discarding a land, which means each cast both pays for itself in fodder and grows the next harvest by one. Discard a land to retrace, that land joins the count, you sweep your battlefield back up next time the spell comes around. It turns a graveyard full of dead lands (the cards every other deck has stopped caring about by the midgame) into a recurring board presence, and it does it without ever needing to draw the card again. That is the design conceit retrace was built to serve: a payoff that wants you flooded, that treats land-light hands and land-heavy graveyards as the same accumulating fuel. The Golgari color pairing is doing exact thematic work, since black supplies the self-mill and discard outlets that fill the yard and green supplies the lands worth losing. Left alone across a long game, it is a faucet you cannot fully turn off, each cast a little wider than the last.