Body Smith

Perhaps they sought a solution to a prior injury, perhaps they were struck by a destructive need to overcome the boundaries of flesh and bone.  Subject to the curiosity either of their own ingenuity or maybe that of another, the Body Smith has found such fascination in the efficiency of their creations that they’ve come to hone the humanoid body with their magically imbued creations.  While their hearts and soul remain, their extremities have been sculpted by arcane steel precision engineered to serve as whole limb replacements. How far their obsession for perfection may go is only limited by the tolerance the individual possesses to put themselves through these painful procedures.

Tool Proficiency

When you adopt this specialization at 3rd level, you gain proficiency with jeweler's tools. If you already have this proficiency, you gain proficiency with one other type of artisan’s tools of your choice.

Body Smith Spells

Starting at 3rd level, you always have certain spells prepared after you reach particular levels in this class, as shown in the Body Smith Spells table. These spells count as artificer spells for you, but they don’t count against the number of artificer spells you prepare.

Body Smith Spells

Artificer Level	Spell
3rd	inflict wounds, bane
5th	alter self, enlarge/reduce
9th	vampiric touch, beacon of hope
13th	fabricate, resilient sphere
17th	animate objects, arcane hand

What Doesn't Kill You

When you reach 3rd level, you can show off your expertise over the clockwork precision of your body both artificial and natural.  You gain the mending cantrip if you do not already know it, and throughout a day you can use this spell a number of times equal to your intelligence modifier during short rests to restore 2d6 hit points per use.  A long rest will restore your number of uses to full. Regular hit dice can be used instead in the midst of battle as a bonus action. You still only recover half your total hit dice per long rest.

You’ve developed a keen eye for finding the exact piece of equipment you need to improve your physique in your quest to attain the perfect performance you seek.  You gain advantage on investigation rolls when scavenging enemies after battles. If the item you find is metallic, you can also immediately attune your finds by replacing your parts with a DC 15 tinkering check, but this does cost the destruction of the item whether or not you succeed.

A Good Defense Is Your Best Offense

At 3th level, you’ve gained enough first person experience to meld finesse of form with functionality in battle.  

• You’ve meticulously examined every injury and mar in your equipment after your battles to know where on your being most needs reinforcement, giving you a +1 to AC.  
• Your modifications have been specialized to further service you in combat.  Your unarmed strikes count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.  You can use Intelligence instead of Strength for the attack and damage rolls, dealing 1d6 plus your Intelligence modifier slashing damage.  At 8th level, the damage dice becomes 1d8, at 12th level the damage dice become 1d10, and at 15th level the damage dice become 1d12. These strikes can count as a magical attack for Arcane Armament once at 5th level, and they can benefit from any damage bonus item or status granting alteration.

Extra Attack

Starting at 5th level, you can attack twice, rather than once, whenever you take the Attack action on your turn.

Charged Up

Your modifications are fueled by arcane power. 

At 9th level, you are situationally immune to magical damage (cold, fire, lightning, thunder, necrotic, radiant). Upon being hit, make a DC 13 Constitution saving throw.  Upon success, you take no magical damage and add 1d6 damage of the captured energy type to your next melee or unarmed strike.  These charges can stack adding additional d6’s to the unleashed energy so long as you succeed on higher Constitution saving throws. 

The second charge is a DC 15, the third a DC 17, the fourth a DC 19, etc. until such a time you use the energy or fail the roll. Upon failing the roll, you prove to only be resistant to magical damage.  Roll the number of d6’s stored and take half damage.

Maximum Efficiency

At 15th level, you’ve become a master at streamlining the humanoid body.  Precise engineering and careful augmentation have given you the extraordinary abilities the natural body sorely lacks.

• Eyes: you gain proficiency on perception checks.
• Arms: you gain advantage on strength saving throws.  Your climbing speed is doubled.  
• Legs: your walking speed is now 10 ft faster.  So long as you land on your feet with a successful acrobatics or athletics check, you take halved fall damage.
• Body: you gain +1 AC.  Your charged magical melee attacks become 2d6 per successful constitution save.

image credit to Maksym Haydar 
it's my first homebrew so any and all feedback would be wonderful