Graf Reaver

Black rarely gets to kill a planeswalker outright, without an attack step and without paying an edict tax that lets the opponent choose. This two-mana 3/3 Zombie folds that answer into a body: feed the exploit trigger a creature on entry, and a target walker dies immediately, on the way in. That makes it removal wearing a threat, which is unusual pricing for a color that normally taxes walker-hate through combat or life payment. The catch is that exploit fires once, so the destruction clause is a single-use answer bolted to a creature rather than a repeatable engine. You are not looping anything; you are casting a walker-kill that happens to leave a 3/3 behind. The upkeep self-damage is the price of that convenience, a slow clock the card points at its own controller. Because the walker-kill already resolved when the Reaver entered, every turn the body sticks around is a turn it does nothing but ping you for one, which nudges you to swing it into blockers rather than park it defensively. The sacrifice is not an optional sweetener but the literal cost of the answer, and the creature you keep is on a timer that rewards spending it aggressively. It is interaction that stops paying its keep the moment it stops attacking.