Caustic Crawler

A -1/-1 until end of turn is the cheap end of removal: it kills the X/1s, shrinks a blocker for a turn, but never threatens anything with real toughness on its own. Stapling that ping to landfall reframes the math entirely, turning a one-shot pinprick into a repeatable engine. Each land drop offers another -1/-1, so a steady stream of lands becomes a slow toughness-eroding machine: stack two triggers in a turn (a draw plus a fetch, a ramp spell, a land from a tutor) and a 4/4 drops to a 2/2 for the turn, opening a window to attack through it or trade up in combat. The body is part of the bargain. A 4/3 attacks into a board it is actively softening, and the same trigger that clears a blocker can be aimed defensively at an incoming attacker. The restriction is baked into the timing: each shrink is small, it wears off at end of turn rather than sticking, and nothing happens at all without lands actually entering, so the engine only hums in a deck built to keep hitting drops. That places it in a lineage of black creatures that grind boards down over time rather than answering threats outright, trading the immediacy of a kill spell for the inevitability of repeatable, if temporary, attrition.