Diregraf Colossus

Two engines folded into one body, and the doubling is what turns this from a member of a Zombie deck into the reason to build one. The first half rewards the graveyard you have already filled: it arrives sized to however many Zombie cards you have lost, milled, or sacrificed, so the same effects that fuel the rest of the tribe make this bigger for free. The second half rewards the graveyard you are about to refill: every Zombie spell you cast spawns a tapped token, which means each subsequent Zombie is two bodies instead of one. The tokens entering tapped is the restriction that stops it from being a free swarm: they cannot block the turn they appear and cannot immediately attack, so the snowball is real but delayed by a turn. What makes it a genuine payoff rather than a lord is that it scales in both directions at once, backward into what is buried and forward into what you keep deploying. A single resolved copy converts a hand of cheap Zombies into a board that outpaces removal, because killing one Zombie spell still leaves the 2/2 it made. This is the threat that justifies running thirty cheap creatures of one type and a fistful of self-mill, and the one your opponent has to answer before it ever connects.