Artillerist's Eldritch Cannon-Force Ballista

Creation: You've learned how to create a magical cannon. Using woodcarver's tools or smith's tools, you can take an action to magically create a Small or Tiny eldritch cannon in an unoccupied space on a horizontal surface within 5 feet of you. A Small eldritch cannon occupies its space, and a Tiny one can be held in one hand. Once you create a cannon, you can't do so again until you finish a long rest or until you expend a spell slot to create one. You can have only one cannon at a time and can't create one while your cannon is present.

Magical Object. The Eldritch Cannon can be created as small or tiny. Regardless of size it always has AC 18 and Hp=5 times your Artificer level (manually update hit points at higher levels). If forced to make ability check or saving throw, treat all it's ability scores as 10+0. 

Mending. If the mending spell is cast on the cannon, it heals 7 (2d6). It disappears if it is reduced to 0 hit points or after 1 hour.

Cannon's  Uses. When you create the cannon, you determine its appearance as a flamethrower, force ballista, or a protector and whether it has legs.  On each of your turns, you can take a bonus action to cause the cannon to activate if you are within 60 feet of it. As part of the same bonus action, you can direct the cannon to walk or climb up to 15 feet to an unoccupied space, provided it has legs. 

Force Ballista. Ranged Spell Attack: to hit, range 120 ft., one target. Hit: 9 (2d8) force damage. If the target is a creature, it is pushed up to 5 feet away from the cannon. Make a ranged spell attack using your spell attack bonus.