Ruthless Cullblade

A 2/1 for two that becomes a 4/2 the moment an opponent dips to ten life or fewer, with the upgrade running as a static condition rather than anything that triggers: nothing goes on the stack, nothing needs to resolve, the body simply checks the opponent's life total continuously and reads as a 4/2 whenever the threshold holds. The catch is the condition itself. It does nothing on a fresh board and never bites back the way a recurring upkeep cost or a sacrifice clause would; it sits at a serviceable rate until the race tips, then doubles its power and accelerates the kill. That sequencing is the point. A deck pressuring life totals from the first turn arrives at ten with several turns of clock left, and the boost lands exactly when each point of damage matters most, turning a midrange body into a closer. The tension is that the upgrade comes too late to help when you are behind and is nearly redundant when you are far ahead; it pays off cleanest in the narrow band where the game is genuinely close to over. Aggressive creatures that key their stats off a diminished opponent's life total share this lever: a built-in incentive to keep the pressure on rather than trade away early reach. As Vampire support, it is curve-filler whose upside the deck around it has to earn first.