Null Caller

The activation cost is where the strategic axis lives: every Zombie token here is paid for with a creature card exiled from the graveyard, so the engine converts dead bodies into fresh ones at a fixed rate of four mana and one corpse per 2/2. That is a deliberately slow, mana-hungry exchange, and the design knows it: the body is a 2/4, built to soak damage and survive long enough to grind rather than to pressure anyone. The exile clause is what keeps the loop from spiraling, since each activation permanently retires a creature card instead of recycling it, and the tokens arrive tapped to deny any chance of using them defensively the turn they appear. What makes the recursion distinct from black's usual reanimation is that it does not return the exiled creature at all: it launders graveyard mass into uniform 2/2s, trading whatever was buried for raw, repeatable token volume. That puts it in a different lane from the Gravecrawler-style self-recursion or the big-reanimation payoff; this is an attrition piece for a deck that expects to outlast, not outrace, and treats its own dead as ammunition for a mana sink that never runs dry as long as creatures keep dying.