Phyrexian Obliterator

The quadruple-black cost is the first thing this creature tells you about itself, and it is doing two jobs at once: it polices what kind of deck can field a 5/5 trampler for four, and it broadcasts the punisher logic stamped onto the body. The sacrifice clause inverts the normal math of combat, triggering on damage dealt to the creature and taxing the dealer a permanent for every point. The trap is that the penalty does not care whether the creature survives. A burn spell that deals lethal damage still hands the dealer a bill: the damage is dealt, the ability triggers, the creature dies to state-based actions, and the trigger then resolves anyway, forcing the source's controller to sacrifice that many permanents. Killing it with damage is the most expensive way to do it. Chump-blocking is the cruelest version: a one-power token dies in combat, and the trigger still resolves, so the blocking player sacrifices a separate permanent on top of the body they already fed it. The seam is that the trigger keys on damage and nothing else. Edicts, destroy, exile, and -X/-X all walk past it clean, paying no permanents. It is not unkillable; it is a wall built specifically against the damage-based answers most decks reach for first. Where other black punisher creatures levy their toll in life or cards, the bill here is paid in permanents, which makes the asymmetry unusually steep.