Vampire Hounds

A creature that eats its own kind to grow, and the line is the whole pitch: pay the same body twice, once on the battlefield and once from the hand. The discard cost is unrestricted (any creature card, no tribal gate, no mana attached), which means the pump is repeatable as fast as your hand can feed it, and the size of the boost is fixed regardless of what you throw in. That parameter is what makes the design hum and what dates it: a small black beater with a hungry mouth fits a graveyard-as-resource plan, where discarding a creature is not a loss but a deposit. The card was built before that plan had the recursion tools to pay it off; it asks you to put creatures in the bin without giving you a way to get them back, so the engine runs hot but burns one direction. As an early experiment in turning discard from a downside into an activation cost, it points at where black would eventually go, when reanimation and madness-style payoffs caught up to the idea that the graveyard is just a second hand. On its own it is a sacrifice of card advantage for a temporary swing, but the structural notion (a creature whose mouth is a discard outlet) is the seed of a lineage black has returned to many times since.