Upgraded Steel Defender

Might of the Master. The following numbers increase by 1 when your proficiency bonus increases by 1: the defender’s skill and saving throw bonuses (above), the bonuses to hit and damage of its rend attack, and the number of hit points restored by its Repair action (below).

Vigilant. The defender can’t be surprised.

Steel Defender. In combat, the steel defender shares your initiative count, but it takes its turn immediately after yours. It can move and use its reaction on its own, but the only action it takes on its turn is the Dodge or Attack action, unless you take a bonus action on your turn to command it to take one of the actions in its stat block or the Dash, Disengage, Help, Hide, or Search action.

If the mending spell is cast on it, it regains 2d8 hit points. If it has died within the last hour, you can use your smith’s tools as an action to revive it, provided you are within 5 feet of it and you expend a spell slot of 1st level or higher. The steel defender returns to life after 1 minute with all its hit points restored.

UPGRADES

Defensive Array. By upgrading the steel defender's protective plates and shielding, you allow it to defend itself more effectively. The defender can now use shields and always has a shield available.

Extra Attack. Faster moving appendages allow the steel defender to attack rapidly. The defender can make two Force-Empowered Rend attacks whenever it takes that action on its turn.

Longer Reach. You increase the reach of your steel defender’s melee attack, by adding spring-loaded arms. The defender's range for Force-Empowered Rend increases by 5 feet.

Hair Trigger Springs. By honing your steel defender’s reaction times, it becomes able to avoid damage with lightning reflexes. When forced to make a dexterity saving throw to avoid taking damage, the defender takes half damage on a failed save, and no damage on a success.

Hot Juicy Flamer.  As an action, the defender can send out a blast of fire. Each creature in a 5 ft wide 60 ft line starting from the defender extending in a direction of your choice must make a Dexterity saving throw against you spell save DC. A target takes 8d6 fire damage on a failed save, or half as much damage on a successful one. This damage increases to 10d6 at 13th level and 12d6 at 17th level. Once your defender uses this feature, you must finish a short or long rest before it can use it again.

Force-Empowered Rend. Melee Weapon Attack: +6 to hit, reach 5 ft., one target you can see. Hit: 1d8 + 4 force damage.

Repair (3/Day). The magical mechanisms inside the defender restore 2d8 + 4 hit points to itself or to one construct or object within 5 feet of it.

Deflect Attack. The defender imposes disadvantage on the attack roll of one creature it can see that is within 5 feet of it, provided the attack roll is against a creature other than the defender.