Ackren’s Arcane Artillery

Surrounding materials gather and form one of three objects from the list down below. Until the spell ends, if you’re within 60 feet of the object, you can use your action to aim or move the chosen object and as a bonus action fire the object. You can move the objects up to 40 feet.

If you cast this spell on another creatures space the target must succeed on a Dexterity saving throw against your spell save DC. On a success, the creature is pushed 5 feet away from the object. On a failure, the creature is knocked prone, restrained, and takes 5d10 bludgeoning damage. As an action, the creature can make a Strength saving throw against your spell DC. On a success, the creature is no longer restrained and pushed 5 feet away from the object. On a failure, the creature is still prone and restrained. If the object moves away from the creature, the creature is freed from the object, no longer being restrained.

Instead of using your action or bonus action to aim and move or fire the object, another creature of your choice can take control of the object if the object can be controlled manually. On the creatures turn it can aim the object as an action and fire it as a bonus action. You still have complete control over the object and can fire and aim it yourself even if another creature is trying to fire and aim it. The creature manually taking control of the object can only push the object up to half its speed.

When the spell ends, any material used to create the objects falls to the ground in the space the object was occupying. If the objects hit points drop to 0, it is destroyed and the spell ends. The area of the destroyed object is considered difficult terrain.

Casting the same objects once every 7 days for one month makes those objects permanent until destroyed.

Ballista. Large object

Armor Class: 15
Hit Points: 50
Damage Immunities: poison, psychic

This ballista is a massive crossbow that fires heavy bolts of force. Four Medium wheels support the Ballista, allowing it to move and be pushed. Before it can be fired, it must be aimed. The Ballista is always loaded, no action required. It takes one action to aim it, and one bonus action to fire it.

Bolt. Ranged Spell Attack: Spell Attack Bonus or, if another creature is using the object, Ranged Weapon Attack: +6 to hit, range 120/480 ft., one target. Hit: 22 (4d10) force damage.

Ram. Large object
Armor Class: 15
Hit Points: 75
Damage Immunities: poison, psychic

This ram consists of a movable gallery equipped with a heavy log suspended from two roof beams by chains. The log is shod in spectral force and used to batter through doors, barricades and people. Four heavy Medium wheels support the Ram, allowing it to move and be pushed. Because of the gallery roof, creatures under it have total cover against attacks from above. The Ram does not need to be aimed.

Ram. Melee Spell Attack: Spell Attack Bonus, other creatures can’t take control of the Ram, reach 5 ft., one object. Hit: 16 (3d10) force damage.

Mangonel. Large object
Armor Class: 15
Hit Points: 100
Damage Immunities: poison, psychic

This mangonel is a type of catapult that hurls heavy balls of arcane force in a high arc. This payload can hit targets behind cover. Four Medium stone wheels support the Mangonel, allowing it to move and be pushed. Before the mangonel can be fired, it must be aimed. The Mangonel is always loaded, no action required. It takes two actions to aim it, and one bonus action to fire it.
A mangonel typically hurls a heavy ball of force, although it can hurl other kinds of projectiles, with different effects. 

Mangonel Stone. Ranged Spell Attack: Spell Attack Bonus, or if another creature is using the object, Ranged Weapon Attack: +5 to hit, range 200/800 ft. (can't hit targets within 60 feet of it), one target. Hit: 27 (5d10) force damage.

At Higher Levels. When you cast this spell using a spell slot of 8th level or higher, you can create one extra object.