Arcane Turret (Guardian)

Artificer Creation. The guardian is a magical object that occupies its space and that has crablike legs. It has an AC of 18 and a number of hit points equal to five times your artificer level. It is immune to poison damage, psychic damage, and all conditions. If it is forced to make an ability check or a saving throw, treat all its ability scores as 10 (+0). If the mending spell is cast on it, it regains 2d6 hit points. It disappears if it is reduced to 0 hit points or after 10 minutes. You can dismiss it early as an action.

On each of your turns, you can take a bonus action to cause the guardian to activate if you are within 60 feet of it. As part of the same action, you can direct the guardian to walk or climb up to 15 feet to an unoccupied space.

You can summon a guardian once for free and must finish a long rest before doing so again. You can also summon the guardian by expending a spell slot of 1st level or higher. If you summon a second guardian, the first guardian disappears.

Bound. The shield guardian is magically bound to an amulet. As long as the guardian and its amulet are on the same plane of existence, the amulet's wearer can telepathically call the guardian to travel to it, and the guardian knows the distance and direction to the amulet. If the guardian is within 60 feet of the amulet's wearer, half of any damage the wearer takes is transferred to the guardian.

Spell Storing. An artificer who wears the shield guardian's amulet can cause the guardian to store one spell of 4th level or lower. To do so, the wearer must cast the spell on the guardian. The spell has no effect but is stored within the guardian. When commanded to do so by the wearer or when a situation arises that was predefined by the artificer, the guardian casts the stored spell with any parameters set by the original caster, requiring no components. When the spell is cast or a new spell is stored, any previously stored spell is lost.

Detonate. As an action, you can command your guardian to detonate if you are within 60 feet of it. Doing so destroys the turret and forces each creature within 10 feet of it to make a Dexterity saving throw against your spell save DC, taking 3d6 force damage on a failed save or half as much damage on a successful one.

Multiattack. The guardian makes two shield bash attacks.

Shield Bash. Melee Weapon Attack: Make a touch spell attack, originating from the guardian, at one creature within 5 ft. of it. On a hit, the target takes 2d6 bludgeoning damage. This damage counts as magical for the purposes of overcoming damage reduction. 

Shield. When a creature makes an attack against the wearer of the guardian's amulet, the guardian grants a +2 bonus to the wearer's AC if the guardian is within 5 feet of the wearer.