Silent Assassin

Deathtouch makes blocking a small attacker a fool's gamble; this 2/1 inverts that math without the keyword. The defender's wall survives the swing, shrugs off two damage, walks away clean, and then dies anyway if the controller sinks four mana into the kill once combat is joined. That makes the durable blocker, the one combat would otherwise spare, into the target combat math cannot account for. The activation taps nothing, and crucially the Assassin need never enter the red zone itself: the ability fires on any blocking creature, so the card does its best work from the sidelines while other attackers draw blocks. Because the cost demands no tap and no body commitment, mana is the only ceiling. With enough open, you can fire it again and again as a single combat winds down, executing blocker after blocker rather than picking off one and stopping. The strategic axis it shifts is the defender's calculus: stopping a fragile attacker is no longer free, because the price of stopping it might be every creature that did the stopping. The faction it belongs to was built around tutoring chains and ferrying small creatures into play rather than around combat, which makes an Assassin that punishes the act of blocking sit crosswise to its kin. It does not want to attack so much as it wants the opponent to commit to defense, then taxes that commitment one corpse at a time.