Terror Ballista

Seven generic mana buys a removal engine dressed as a beater, but the sacrifice clause is the hinge: the construct wants to swing into a board it can eat, converting your own creatures into targeted kills the moment it is declared as an attacker. That trigger fires on attack declaration, before blockers are chosen, so the destroy effect never depends on the construct surviving combat or the attack connecting. Menace pushes in the same direction from another angle: forcing two blockers or none means every profitable swing either eats an opponent's body outright or clears a lane, and it protects the attack from a single chump. The asymmetry is what makes the sacrifice palatable (you feed it your own creature, an opponent's creature dies), which is why it belongs in sacrifice-fueled shells where the eaten body was already spoken for, turning a construct with no colored pip into a black-adjacent kill machine. The color identity surfaces only in the graveyard: unearth for returns it with haste for one lethal swing before exile, so the removal trigger can fire again even after the body has died once. A colorless removal engine is dangerous precisely because any deck can hard-cast it, so the recursion that grants a second attack is gated behind two black mana. That gate is what keeps the reusable version an honestly black effect rather than a free rider in every artifact deck.