Wall of Mulch

Sacrifice a Wall, draw a card: that activation turns a stack of defensive bodies into a grindy card-advantage engine, and the key is the wording. The cost names a Wall, not itself, so the engine can eat every other blocker on the table while this 0/4 keeps standing to fire again. Walls are normally a dead-end type, all toughness and no plan, and this hands them an exit: every defensive body you played to survive becomes a card later, and the loop compounds when the Walls themselves replace the ones they feed to the engine. The design leans on tribal critical mass from the opposite direction it usually runs, asking you to assemble a pile of a creature type that otherwise just sits there. The friction is the green mana per draw and the steady loss of board presence; you are trading defense for cards one at a time, never for free, and you eventually run out of fodder. A 0/4 for that cannot attack is, on its own, a road bump. The value is entirely in the repeatable activation, and the template (sacrifice a creature of a fixed type to draw) has surfaced in graveyard and aristocrats designs in the years since.