Phyrexian Plaguelord

The body is the floor, not the ceiling: a 4/4 for five trades fine on its own, but the real engine is the two sacrifice abilities stacked on one creature. The cheap line costs no mana and no tap, just a creature, and it shrinks a target by -1/-1 as many times as you have fodder to feed it. Activate it repeatedly off a swarm and you can lay a board of small attackers flat at instant speed, or chip one threat down across several activations. The tap line is the finisher: -4/-4 by eating the Plaguelord itself, which doubles as a sacrifice outlet for whatever death payoff is waiting in the wings. What makes the design hold together is the division of labor. The free ability is the sink, turning tokens, dorks, and dying creatures into repeatable removal that never asks for mana once it is online; the tap-and-self-sacrifice ability is the closer that cashes the body in for a bigger swing. That split made it a natural centerpiece for early sacrifice decks built around saprolings and recursive bodies, where it both consumed its own swarm and policed the opponent's. The card is a hinge between go-wide creature production and reactive, instant-speed removal, charging nothing but creatures to keep firing.