Martyred Rusalka

The effect reads strangest in what it refuses to do. Pay a white mana, sacrifice a creature, and the target simply can't attack this turn: it stays on the battlefield, keeps its blocking, keeps every other ability, and comes back next turn unbothered. You have rented one combat phase off one creature's offense, nothing more. The timing constraint is the heart of it: a "can't attack" effect only matters before attackers are declared, so this is a thing you do in the upkeep or main phase of the player about to swing, preempting the alpha strike rather than answering one. Miss the window and the ability is dead for the turn. The sacrifice half carries as much weight as the deny half. The fuel must be a creature: a Spirit token, a mana dork whose job is done, a creature you were going to lose anyway. In a shell wired around death triggers, the ability stops being a defensive trick and becomes a sacrifice outlet that happens to tax an opponent's offense on the way out, which is the seam this body sits in: half aristocrats engine, half preemptive delay, two jobs that rarely share a frame this cheap. The cost structure keeps either half from running away. Every activation wants a mana and a creature, the effect touches only attacking and only this turn, never blocking and never removal. You are buying time, not an answer, and you pay for it each time you ask.