Trebuchet

Large object Armor Class: 13 Hit Points: 160 Damage immunities: poison, psychic Cost: 8000 gp A piece of siege equipment used to lob extremely large stones at enemy castles. A trebuchet could use different ammunition with varying effects, determined by the DM.
Launch Rock: Ranged Weapon Attack: +5 to hit, range 600 ft./900 ft., one target. Hit: 27 (6d8) bludgeoning damage. This attack deals double damage to structures.