Eradicator Valkyrie

Boast is the mechanic that finally gave black midrange a reason to keep attacking, and this is the card that made it worth the risk. The Boast ability is edict-shaped, but it prices the aggression carefully: you attack, you feed a creature to the sacrifice cost, and only then does each opponent lose a creature or planeswalker of their choosing. That is a symmetrical trade you break with fodder, and the once-per-turn, must-have-attacked timing means the card cannot sit back and grind edicts from safety. It has to be in the red zone, exposed, before it does anything. The body backs the demand: a 4/3 flier with lifelink swings the clock and the life total the same direction, so the beatdown pays for the attrition. What ties the package together is the hexproof from planeswalkers clause, an unusually narrow protection that reads as flavor until you notice what it does at the table: a creature this aggressive would ordinarily be a prime target for a planeswalker's minus, and this shrug at that entire angle of removal turns a fragile three-toughness body into a reliable pressure valve against superfriends and control alike. Everything here points the same way, toward a creature that wants to be attacking, sacrificing, and draining, all at once, every turn it survives.