Baliste Ogre

Large object
Armor Class: 15
Hit Points: 50
Damage Immunities: poison, psychic
Bolt. Ranged Weapon Attack: +6 to hit, range
120/480 ft., one target. Hit: 16 (3d10) piercing
damage.
A ballista is a massive crossbow that fires heavy
bolts. Before it can be fired, it must be loaded
and aimed. It takes one action to load the weapon,
one action to aim it, and one action to fire it.