Conjure Ballista

You summon a large magical Ballista within range that can be climbed into and fired. The Ballista is size large with an AC of 15, 50 hit points, and has immunity to poison and psychic damage. Rather than taking 3 actions to load, aim, and fire like normal Ballista this Ballista magically loads itself taking only 1 action to aim and fire but you must be manning the Ballista to do so. Climbing into and out of the ballista follows the same rules as mounting. While in the Ballista you can use an action to fire it at a target, it has a range of 120ft/480ft, make a ranged spell attack using the spell attack of the caster that summoned the Ballista. If you hit, the target takes 3d10 + (spell modifier of the caster) piecing damage that is considered magical.