Sek'Kuar, Deathkeeper
Death becomes a board, and the conversion rate is what makes the engine run: every other nontoken creature that dies on your side replaces itself with a 3/1 that can swing the same turn. The 4/3 body is fragile enough that opponents will aim removal at Sek'Kuar to switch off the factory, but the deeper cost is buried in one word. The trigger reads "nontoken creature," which means the Graveborn tokens it produces cannot themselves feed it. That clause is the entire balancing act: an unrestricted haste-token-per-death engine would loop on its own output and snowball into a closed circuit, so the design forces you to keep spending real creatures (sacrifice fodder, chump blockers, bodies worth dying twice) to keep the wheel turning. The Jund color identity sits at the meeting point of aristocrats and reanimation, and the haste keyword on the tokens is the detail that turns value into pressure: a board wipe or a sacrifice chain converts directly into an attacking force rather than a stalled mob. As an aristocrats payoff, this design predates most of the genre's marquee enablers, which gives it a quieter reputation than its raw throughput deserves. The Graveborn tokens are creature-type window dressing, but their stat line does honest work: a 3/1 that hits hard and trades down keeps the board churning, even though it can never trigger the engine that made it.
