Upon stumbling into the ancient ruins of an alien vessel, you found what appeared to be a suit of some kind, like an exoskeleton. As you examined the item, moved on its own, attaching itself to you, piercing your skin in several places, permanently melding itself with your body. It pierced the back of your neck at the base of your skull, connecting your mind to the suit, making it truly an extension of your body. You control the suit as you would control one of your own limbs. The suit is made up of a belt, a spine that connects at the base of your skull, arms that extend out from the spine and trace your arms, connecting to your body at the shoulders, elbows, wrists, and hands, attaching to your individual fingers, and legs that connect to your body at the hips, knees, and ankles. It is made of an alien metal that is not found anywhere on the earth. It seems to power itself, however there is no obvious battery anywhere on the armor. When it moves, it is almost completely silent, only making the slightest sounds. It has become a part of you, giving you abilities and power beyond any conventional weapons. The more you use the suit, the more powerful it becomes, and the more it changes and adapts itself.

Note: If you are starting in a game from level 1 and wish to choose this subclass, you may want to speak with your DM about the appearance of your character before level 3, as the fighter does not get to choose a Martial Archetype until level 3. The suit bonded itself to you before the game takes place, but it does not grant you any additional abilities until level 3, or whatever explanation you want to come up with. Or perhaps you discover the suit in-game. Either way, speak with your DM to determine how that all shakes out. 

Note2: I highly recommend that you take some artistic license with the appearance of the exoskeleton, from what it looks like while attached to you what the weapons look like. For example, the War Blade ability could be a greatsword, greataxe, or even a warhammer. Make this your own. Customize what the weapons and abilities look like. If it would make more sense for one of the weapons to deal bludgeoning damage rather than slashing, go for it. Clear everything with your DM, but this subclass is designed to make you feel awesome while not being overpowered. (or at least not too overpowered.)

Exoskeleton Configuration

When you choose this Archetype at 3rd level, you choose one of the following configurations for your exoskeleton. This configuration will determine how your exoskeleton evolves and changes as you gain levels.

Power Charges: You have an amount of power charges equal to half your level rounded down, which are used to power your exoskeleton abilities. You regain all expended power charges after completing a long rest.

Evolved Armor: The exoskeleton evolves to form armor around you, determined by the configuration you choose. You are unable to wear armor because of the exoskeleton.

Saving Throws: Some of your abilities require enemies to make a saving throw. Your save DC is equal to 8 + your proficiency + your Strength or Dexterity modifier (whichever is higher.)

Bladed

Moderate Armor: Your AC becomes 15 + your Dexterity modifier (max 2).

Proto-Blade: You have a Proto-Blade that extends from one of the forearms of the your exoskeleton (you choose which arm) into your hand. As a bonus action, you can expend one power charge to extend the sword into your hand for 1 minute, after which the blade automatically retracts into the exoskeleton. The blade stays connected to the exoskeleton by the butt of the handle, connecting to the wrist of the exoskeleton. If you drop the blade, it automatically retracts into the exoskeleton, and must be extended again as a bonus action, expending another power charge. You are proficient with the blade, which has a reach of 5 ft. and deals 1d8 slashing damage. This damage increases by 1d8 at 7th, 10th, and 15th level.

Heavy Bladed

Heavy Armor: Your AC becomes 18.

War Blade: You have a war blade that splits in two and collapses into the arms of your exoskeleton. As a bonus action, you can expend one power charge to extend your War Blade, attaching the handle to your wrist. If you drop the War Blade, it automatically splits and retracts into the exoskeleton and must be extended again as a bonus action, expending another power charge. The blade lasts for 1 minute and then retracts into the exoskeleton. The War Blade has the Heavy and Two-Handed properties. You are proficient with the War Blade, which has a reach of 5 ft. and deals 1d12 slashing damage. This damage increases by 1d12 at 7th, 10th, and 15th level.

Heavy Ranged

Moderate Armor: Your AC becomes 15 + your Dexterity modifier (max 2).

Nightmare Rifle: You have a heavy laser rifle that collapses into the arms of your exoskeleton. As a bonus action, you can expend one power charge to extend the rifle, attaching it to the wrist of the exoskeleton by the grip of the rifle. If you drop the rifle, it automatically retracts into your exoskeleton and must be extended again as a bonus action, expending another power charge. The Nightmare Rifle has the Heavy and Two-Handed properties. You are proficient with the rifle, which has a range of 120/360 ft. and deals 1d10 cold damage in a concentrated bolt. The rifle lasts for 1 minute and then retracts into your exoskeleton. The damage increases by 1d10 at 7th, 10th, and 15th level.

Light Bladed

Light Armor: Your AC becomes 12 + your Dexterity modifier.

Hidden Blades: You have two hidden blades in the two arms of your exoskeleton. As a bonus action, you can expend one power charge to extend one of the blades into your hand, or two power charges to extend both blades into your hands. The blades stay connected to the exoskeleton by the butt of the handles, connecting to the wrists of the arms. If you drop a blade, it automatically retracts into the exoskeleton, and must be extended again as a bonus action, expending another power charge. The blades last for 1 minute and then retract into the exoskeleton. The Hidden Blades have the Finesse and Light properties. You are proficient with the hidden blades, which have a reach of 5 ft. and deal 1d6 plus your Dexterity modifier slashing damage. This damage increases by 1d6 at 7th, 10th, and 15th level.

Light Ranged

Light Armor: Your AC becomes 11 + your dexterity modifier.

Terror Pistol: You have a laser pistol that collapses and is stored in one of the arms of the exoskeleton (you choose which arm). As a bonus action, you can expend one power charge to draw the pistol into your hand. The pistol stays connected to your wrist by the grip. If you drop it, it automatically collapses into the wrist of the exoskeleton, and you must extend it again as a bonus action, expending another power charge. The Pistol has the Light property. You are proficient with the pistol, which has a range of 40/120 ft. and deals 1d6 radiant damage. The pistol lasts for 1 minute and then automatically collapses into the exoskeleton. The damage of the pistol increases by 1d6 at 7th, 10th, and 15th level.

Ranged

Light Armor: Your AC becomes 12 + your Dexterity modifier.

Punch Rifle: You have a laser rifle that collapses into the arms of your exoskeleton. As a bonus action, you can expand one power charge to extend it as a bonus action, attaching it to your wrist by the grip of the rifle. If you drop the rifle, it automatically retracts into the exoskeleton and must be extended again as a bonus action, expending another power charge. The rifle lasts for 1 minute and then retracts into the exoskeleton. The Punch Rifle has the Heavy and Two-Handed properties. You are proficient with the rifle, which has a range of 100/300 ft. and deals 1d8 lightning damage in a concentrated bolt. This damage increases by 1d8 at 7th, 10th, and 15th level.

Configuration Enhancement

You gain one of the following upgrades to your exoskeleton, depending on the configuration you chose.

CQB - Light Ranged

Starting at 7th level, you are no longer disadvantaged when making a ranged attack within 5 ft. of a hostile creature. Additionally, you gain a +1 bonus to attack and damage rolls made with ranged weapons when there is more than one enemy within 5 ft. of you.

Energy Shield - Bladed

Starting at 7th level, the exoskeleton can project a shield of pure lightning energy from your one of your forearms. As an action, you can expend two powers charge to activate the shield, choosing one of the following options. The shield can be deactivated as a bonus action.

Partial Shield: A normal sized shield made of pure lightning energy, granting +2 AC and resistance to lightning damage. If an enemy scores a critical hit against you, the shield is deactivated. The shield lasts for 1 minute or until deactivated.

Full Shield: A shield that extends to the ground, across your body, and above your head, granting you full cover. You cannot make attacks while projecting this shield. The shield has an AC of 10, 1/4 of your hit point maximum, and resistance to lightning damage. If the shield is reduced to 0 hit points, or an enemy scores a critical hit against the shield, it is deactivated. The shield lasts for 1 minute or until deactivated.

Enhanced Optics - Heavy Ranged

When you make an attack with your Nightmare Rifle, you score a critical hit on a roll of 19 or 20.

Jump Jets - Light Bladed

Your exoskeleton gains a pair of jump jets on the backs of your shoulders and reinforces the legs of the exoskeleton, granting you advantage on saving throws against fall damage. When you move using the jump jets, you do not use your movement speed. As a bonus action, you can activate your jump jets, expending an amount of power charges determined by the function you use. You can use your jump jets only once per turn. Choose from the following list of functions:

Launch - 1 Power Charge: Your jump jets launch you up to 15 ft. in any direction.

Disengage - 1 Power Charge: Your jump jets propel you backwards 5 ft. Enemies do not get opportunity attacks if you move out of their reach with this movement.

Barge - 2 Power Charges: If an enemy is within 5 ft. of you, you can use your jump jets to propel yourself into them, forcing them to make a Strength saving throw, being pushed 10 ft. away from you and knocked prone on a failed save.

Lightning Burst - Ranged

Starting at 7th level, when you take the attack action with the Punch Rifle, you can expend two power charges to turn your shot into a short range burst of lightning energy. Make a ranged attack against a target within 5 ft. of you, dealing 2d8 bonus lightning damage on a hit. The bonus damage increases by 1d8 at 10th level and again at 15th level.

Power Gauntlets - Heavy Bladed

Starting at 7th level, your exoskeleton forms reinforced gauntlets on your hands. You become proficient in unarmed strikes, and your unarmed strikes deal 2d6 + your Strength modifier bludgeoning damage. Additionally, when you hit a creature with a melee attack, you can expend one power charge to make an unarmed strike against the same target.

Enhanced Prowess

When you gain this feature at 10th level, you can increase your Strength, Dexterity, or Constitution ability score by 2. Additionally, you gain proficiency in the Acrobatics or Athletics skill (you choose).

Configuration Enhancement II

You gain one of the following upgrades to your exoskeleton, depending on the configuration you chose.

Duelist - Bladed

You specialize in one on one combat, exploiting your targets weaknesses. Starting at 15th level, if there is only 1 hostile creature within 5 ft. of you, you can expend a number of power charges, determined by which benefit you choose, to gain one of the following benefits against the hostile creature for 1 minute. The effect ends if the creature gets further than 5 ft. away from you or another hostile creature comes within 5 ft. of you. You can have only one of the following effects active at a time:

• You gain a +1 bonus to attack and damage rolls made against the creature (1 Power Charge).
• You gain a +1 bonus to AC against the creature (1 Power Charge).
• You gain advantage on attack rolls made against the creature (2 Power Charges).
• The creature has disadvantage on attack rolls against you (2 Power Charges).

Flashbang - Light Ranged

Starting at 15th level, your exoskeleton can emit a short range blinding flash from the wrist. As a bonus action, you can expend one power charge to flash one creature within 5 ft. of you. That creature must succeed on a Constitution saving throw or be blinded for one minute. They can repeat the saving throw at the end of each of their turns, ending the effect on a success. Additionally, you can expend four power charges to overcharge the flash, forcing all creatures within 10 ft. of you to make the saving throw. You are immune to the effects of the flash.

Improved Jump Jets - Light Bladed

Starting at 15th level, when you use your jump jets, you can immediately use your jump jets again, assuming you have enough power charges, using either the same function or a different function. Additionally, you gain the following functions for your jump jets:

Flying Attack - 2 Power Charges: You use your jump jets to launch yourself at a hostile creature within 15 ft., making an advantaged attack with one of your Hidden Blades upon reaching them. If the attack hits, it deals an additional 1d6 slashing damage. You must already have at least one of your Hidden Blades extended to use this function.

Long Shot - 2 Power Charges: You put your jump jets on overdrive and launch yourself 60 ft. in any direction. If you run into an object or creature before reaching 60 ft., both you and the thing you ran into must succeed on a DC 15 Dexterity saving throw or take 1d6 bludgeoning damage for every 10 ft. you traveled before colliding. If you ran into an object, the object automatically fails the saving throw.

Recovery Burst - 1 Power Charge: Whenever you are knocked prone, you can activate your jump jets as a reaction, immediately propelling yourself back to your feet, but not moving.

Juggernaut - Heavy Bladed

Starting at 15th level, as a bonus action, you can expend a number of power charges, determined by the effect you choose, to reconfigure your armor to grant greater defense, sacrificing maneuverability. The reconfiguration lasts until you deactivate it or until a hostile creature scores a critical hit against you. When you activate this feature, choose one of the following effects:

• +2 AC, -10 ft. movement speed (1 Power Charge)
• +4 AC, -20 ft. movement speed (2 Power Charges)
• +8 AC, -30 ft. movement speed (3 Power Charges)

Overcharge - Ranged

Starting at 15th level, you can overcharge your Punch Rifle. When you take the attack action with your Punch Rifle, you can expend a number of power charges to overcharge a single shot. Choose one of the following effects for the shot:

• 1 Power Charge - If the attack hits, the target is knocked prone.
• 2 Power Charges - If the attack hits, it deals 2d8 bonus damage.
• 4 Power Charges - If the attack hits, it deals 4d8 bonus damage.
• 6 Power Charges - The attack is a critical hit and deals maximum damage.

Weak Spot - Heavy Ranged

Starting at 15th level, when you score a critical hit with your Nightmare Rifle, the attack deals maximum damage.

Configuration Enhancement III

Starting at 18th level, your exoskeleton gains one of the following abilities, determined by the configuration you chose.

Dual Terrors - Light Ranged

Starting at 18th level, when you extend your Terror pistol as a bonus action, you can expend an additional three power charges to extend a second Terror pistol into your other hand. When you take the attack action with the Terror pistol, you can immediately make another attack with your second Terror pistol.

Electrify - Ranged

Starting at 18th level, when you hit a creature with your Punch Rifle, you can expend a number of power charges to electrify the target, chaining lightning to other creatures that get too close. The target must succeed on a Constitution saving throw or become electrified and stunned for one minute, repeating the saving throw at the end of each of their turns, ending the effect on a successful save. While the creature is electrified, any creature that gets within a certain radius of the electrified creature (determined by the amount of power charges expended) must succeed on a Dexterity saving throw or take 2d8 lightning damage.

• 5 ft. - 2 Power Charges
• 10 ft. - 3 Power Charges
• 15 ft. - 4 Power Charges
• 30 ft. - 8 Power Charges

Heated Metal - Light Bladed

Starting at 18th level, you can make your Hidden Blades burn with fire. When you activate your one or both of your Hidden Blades as a bonus action, you can spend a number of additional power charges per Hidden Blade to ignite the blades with fire, adding 1d6 bonus fire damage per additional power charge. (Example: igniting one Hidden Blade for 2d6 bonus fire damage would cost an additional 2 power charges, while igniting two Hidden Blades for 2d6 bonus fire damage would cost an additional 4 power charges.)

Marksman's Trance - Heavy Ranged

Starting at 18th level, when you score a critical hit with your Nightmare Rifle, you can expend two power charges to expand your critical hit range by one until the end of your turn. This ability can be stacked.

Ripcord - Heavy Bladed

Starting at 18th level, when you take the attack action with the War Blade, you can expend two power charges to throw it at a target within 15 ft. of you. A chain attaches to the handle and extends from the wrist of the exoskeleton. Make a ranged attack against the target, adding your proficiency and Strength modifiers to the attack roll. If the attack hits, the target takes the War Blade's normal damage as it lodges into them. You reel in the War Blade, choosing to pull yourself to the target or the target to yourself. The target must make a Strength saving throw. On a successful save, the target detaches the War Blade from itself and it reels back to you. On a failed save, you reel the target to yourself at incredible speed, and can make one attack with your gauntlet against the target. Alternatively, you reel yourself to the target at incredible speed, and can make one attack with your gauntlet against the target. If the attack hits, the target is knocked prone.

Shocking Blade - Bladed

Starting at 18th level, when you activate your Proto-Blade as a bonus action, you can expend 2 additional power charges to electrify the blade. Whenever you hit an enemy with your Proto-Blade while it is electrified, the target must succeed on a Constitution saving throw or be stunned. At the beginning of their next turn, they may repeat the saving throw, ending the effect on a successful save. Otherwise, the effect lasts until the end of their turn, unless stopped by other means.