Cystbearer

Infect splits a creature's combat damage into two separate clocks: minus-one/minus-one counters on creatures, poison counters on players. This 2/3 is built to feed the player-facing one, the poison march toward ten, and three toughness is what lets it. Most early poison threats are fragile one- and two-drops that fold to any trade; this body survives a swing from a 2-power blocker, so an opponent cannot stall the race by chump-trading a small creature into it. On the swing back, its damage to a blocker lands as permanent -1/-1 counters, strict upside over ordinary combat damage: a two-toughness blocker dies outright (toughness to zero), and anything larger gets shrunk for good rather than healing up at end of turn. The trade-off the body absorbs is that it is unspectacular by design, a midrange beater rather than a fast one, the rank-and-file member of a poison plan that needs durable threats as much as quick ones. The poison clock lives and dies on connecting repeatedly, and a poison deck's problem is rarely the opening salvo: it is keeping a body in the red zone after the cheap, fragile threats have been answered. This is the creature that keeps applying two poison per swing through a board stall, the durable middle of the curve that lets the player-facing clock survive long enough to finish.