Terror Ballista is a rare Artifact Creature — Construct card from The Brothers' War (BRO), collector number 290. Current market price: $0.33 (foil $0.43), TCGplayer market prices via Scryfall.
Menace Whenever this creature attacks, you may sacrifice another creature. When you do, destroy target creature an opponent controls. Unearth {3}{B}{B} ({3}{B}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)