Putrefax

Math, not midrange. Five poison counters out of the ten that kill is half a clock on the turn it arrives, because haste and trample mean those five points come down the instant it lands, threatening to punch through unblocked or trample past a small blocker. The end-step sacrifice is the whole bargain: this is a one-turn weapon, a green creature that exists to swing once and vanish, and that disposability is what justifies pushing five power's worth of poison through a single combat. Read it as a burn spell wearing a creature's stats. It does not block, it does not race twice, its end-step trigger sacrifices it after just one attack; the design refuses to let it become a threat the opponent must answer turn after turn. That refusal is the point. A 5/3 Infect attacker that stuck around would be a perpetual lethal clock demanding interaction every turn; one that sacrifices itself collapses the decision into a single window. The opponent gets exactly one chance to block, kill it in response, or eat the counters, and after that the danger is gone. The fragile three toughness barely matters when the body is never meant to see a second turn. It rewards the deck that has already built most of the kill and wants the last shove, not the deck shopping for a creature to invest in.