Spark
Starting at 1st level, you have enhanced cognitive process, caused by your spark of geniality. Your access to this spark is represented by a number of spark points. Your combat engineer level determines the number of points you have, as shown in the Spark Points column of the Combat Engineer table.

Your spark points are used to fuel many of your features, like your Insight, detailed bellow. After spending a spark point, it is unavailable to you until you finish a short or a long rest. 30 minutes of this rest should be spending by analyzing mechanical contraptions, studying or planning new inventions.

Some of the features require a saving throw to resist its effects. The Spark save DC equals 8 + your proficiency bonus + your Intelligence modifier.

Insight
You can spend 1 spark point to add your spark die to the result of any Intelligence check or saving throw you make.

Engineering Versatilist
At 1st level, you can add half your proficiency bonus to all checks you make with a tool you aren't already proficient with. Also, you have advantage on your Intelligence checks made to identify problems on mechanical devices or structures.

Modified Weapon
Starting at 1st level, you can choose one weapon of the ones you possess and are proficient with as a combat engineer. You can spend 1 hour working on this weapon to make modifications on it that enhance this weapon in some way, which can be done as part of a short rest. After you’ve used the attack action with your modified weapon, you can use your bonus action to activate the modification. You can only have one of these weapons at time.

Alchemist Fire
You press a button that releases alchemist fire on the blade or point of impact of your weapon (or lit the ammunition on fire, if it is a ranged weapon). On a hit, the target must make a Dexterity saving throw against your Spark save DC or take additional fire damage equal to your spark die. Starting at 5th level, you can reduce the damage die in one size category (d6 to a d4 for example) and cause the enemy to start to burn, taking 1d4 fire damage on the start of each of its turns, or until it takes an action to put of the flames.

Electric Strike
You activate a electric chain surrounds your weapon or a piece of ammunition you shoot. On a hit, the target must make a Dexterity saving throw against your Spark save DC or take additional lighting damage equal to your spark die.

Starting at 5th level, you can reduce the damage die in one size category (d6 to d4, for example) and cause the target to become unable to take reactions until the end of your next turn.

Rocketed Weapon
You add rockets to the opposite side of your weapon, activated to increase the impact on the attack. On a hit, the target must make a Dexterity saving throw against your Spark save DC or take additional bludgeoning damage equal to your spark die.

Starting at 5th level, you can reduce the damage die in one size category (d6 to d4, for example) and shove the target, without taking an action. The contested check is made against your spark save DC.

Powered Armor
You add a force field generator on your armor or shield. While wearing it, you can use your bonus action to gain a number of temporary hit points equal to your spark die. These temporary hit points last until the start of your next turn.

Starting at 5th level, you can reduce the spark die in one size and gain 10 feet of additional movement when you activate the powered armor. This movement doesn't provoke opportunity attacks.

Unconventional Arsenal
At 2nd level, you learn how to create weird weapons and use normal weapons in exotic manners. You need a weapon to modify, and you add one unconventional property to your weapon. You only know how to use one unconventional weapon, learning one more at 14th level.

Oversized Weapon
You develop a oversized weapon, which you can use with the assistance of a specially prepared belt that helps to distribute the weight and glove to better hold it. You must choose any weapon with the heavy property to create this unconventional weapon. An attack with the oversized weapon deal 2 additional damage. In addition, you roll your spark die on a critical hit and add the number rolled to the damage of the attack.

Repetition Weapon
Choose any weapon with the ranged property for this modification. The weapon lose the reloading property, if it has one, and you can choose to forgo an attack you make as part of your Attack action to make two attacks with it at disadvantage.

Versatile Weapon
You create a weapon that works both at ranged and melee distance. You can create the following combinations:

A heavy melee weapon with any ranged weapon
A melee weapon without the light or thrown property with any ranged weapon without the heavy property
You can choose which weapon you are using before making each attack.

Gadgetry
At 2nd level your ability to use your spark of intelligence allow you to modify regular objects into useful gadgets. You create your gadgets during a short or a long rest, by spending 1 spark point per gadget created. Once you spend a spark point to create a gadget, you can regain that spark point until the gadget is used, and the gadget loses its effect.

Activating a gadget requires an action or a bonus action, but you can activate a gadget only once per turn, unless otherwise specified. Once a gadget is used, it becomes a regular object again, unless otherwise specified.

You can use two gadgets as part of the same bonus action when you reach the 10th level, and three gadgets at 15th level.

Also, you can use your action to disassemble any unused gadget you have created and recover the spark points you have spent.

Grappling Gun
Required objects: Grappling hook, crossbow and a 50 ft. rope

You can improvise a grappling gun with the aforementioned objects. When activating a grappling gun, you can attach the grappling hook to any surface within 50 feet. Using a reaction, you can move yourself to the surface in which you have attached the grappling hook.

You can also try to grapple a creature Large or lower within 50 feet of you. On a success, you can move that creature towards your direction.

You can use this gun a number of times equal to the number of spark points you have spent on it.

Enhanced Trap
Required objects: ball bearings, caltrops or hunter's trap

You can deploy the chosen object. The DC to avoid the effects of the object is equal to your Spark save DC, instead of the regular DC of the chosen object. In addition, you can enhance the trap with either alchemist fire or electricity, dealing additional damage equal to your spark die, of fire or lightning type, to the first creature to fail a save DC against your enhanced trap.

Powered Crowbar
Required objects: crowbar

You attach a little engine to a crowbar. You add your Intelligence modifier + your spark die to the next check you make using this crowbar. You can use the crowbar a number of times equal to your Intelligence modifier for each spark point you have spent on it.

Flying Manacles
Required objects: manacles

You can throw this manacle on a target within 30 feet. The target must make a Dexterity saving throw, or is bind to the manacle. The DC to open the manacles is equal to 15 or your spark save DC, whichever is higher. The manacles have a number of hit points equal to your level in this class + yoru Intelligence modifier or 15, whichever is higher.

Dart Thrower
Required objects: dart, melee weapon

You transform the handle of your weapon into a spring action dart thrower. When you make an attack with this weapon, you can activate the dart thrower. The dart thrower is a ranged weapon you are proficient with, with a range of 30/60, and deal damage equal to your spark die piercing damage. If your dart thrower is on your modified weapon, you can activate both as part of the same bonus action.

Briefing
Prior to commencing a mission (adventure), you request an overview and analysis of the area of operations from your superiors. You are briefed via letter on the current situation in the region and some lore about the area (at the DM's discretion). This lore tends to relate to military threats, hazards and potential assets (including some side-quests). Additional information in a briefing may be included at the DM's discretion. Additional letters may be sent at later dates containing additional information.

Automaton Commander
Automaton commanders are engineers that learn how to build automatons, mechanical beings that fight alongside them and obey their commands. Using these machines of war, they are a force to be reckon with in the battlefield.

Automaton
Beginning at 3rd level when you choose this archetype, you learn how to build an automaton. This automaton is created through a complex crafting process that requires you to spend 8 hours and 10 gp worth of materials per level you have on this class, with which you forge its core and fuel it by spending half your maximum amount of spark points.

Upon finishing the process, you must choose a number of models who better suit your needs, and which determine the characteristics of your automaton.

In combat, you decide if either it will roll its own initiative or if it will acts on your turn, matching your initiative. It has its own movement, and take its own actions, and is under your control. While you are unconscious, your automaton can act on its own.

You add your proficiency bonus to the automaton AC, saving throws and skills the automaton is proficient, attack rolls and DC for the automaton traits.

Size
Tiny Automaton. Your automaton is tiny sized. It has a penalty of 4 to its Strength and a bonus of 4 to its Dexterity. It has -2 hit points per level you have on this class. +20 feet movement speed.
Small Automaton. Your automaton is small sized. It has a penalty of 2 to its Strength and a bonus of 2 to its Dexterity. It has -1 hit points per level you have on this class. +10 feet movement speed.
Large Automaton. Your automaton is large sized. It has a penalty of 4 to its Dexterity and a bonus of 4 to its Strength. It has +1 hit points per level you have on this class. -10 feet movement speed.
Weaponry
Slam. Reach 5ft., one target you can see. Hit: your spark die + Strength modifier bludgeoning damage.
Cannon. Reach 60ft., one target you can see. Hit: your spark die force damage.
Blade. Reach. 5 ft., one target you can see. Hit: Your spark die slashing damage + its Dexterity modifier.
Movement
Land. +10 ft. speed
Aerial. -20 ft. speed, fly 20 ft.
Aquatic. -20 ft. speed, swim 30 ft.
Climber. -20 ft. speed, climb 30 ft.
Automaton
Medium construct

Armor Class 8 + your proficiency bonus + your Intelligence modifier

Hit Points 5 + Constitution modifier per level on this class

Speed 30 ft

STR 12 (+1) DEX 10 (+0) CON 12 INT 5 (-3) WIS 10 (+0) CHA 11 (+0)

Saving Throws Constitution, Charisma (use your proficiency bonus).

Skills Athletics, Intimidation, Perception.

Damage Immunities poison, psychic

Condition Immunities blinded, charmed, deafened, frightened, paralyzed, petrified, poisoned

Senses blindsight 10 ft., darkvision 60 ft., passive Perception 10 + your proficiency bonus

Languages none, but understands the engineer.

ACTIONS (Require your Bonus Action)

Automaton Attacks. The automaton is able to perform actions based on your commands. The attack depend on the type of weaponry chosen.

Mechanical Implements
Starting at 7th level, you learn how to improve your automaton with implements. You know two implements when you first choose this specialization, and one additional at, 13th, and 17th levels.

Whenever you gain a level in this class, you can also replace one implement that you already know with a different implement.

Sentinel. (7th level) As a reaction against an attack, you can spend 2 spark points to command your automaton to protect itself or another creature within 5 feet of it. The AC of the creature increases by an amount equal to your Intelligence modifier until the start of your next turn.
Magical Storage. (7th level) Your automaton can store up to three 1st or 2nd-level spells. You must spend a number of spark points equal to 1 + the level of spell to cast it while the spell remains stored.
Flight. (7th level) You can spend 2 spark points to cause your automaton to flight for 1 minute, with a speed of 30 feet. In addition, your automaton can cast feather fall" on himself at will.
Powerful Attacks. (13th level) The attacks made by the automaton are considered magical for the purpose of overcoming resistance and immunity to nonmagical damage. In addition, you can spend 3 spark points to allow the automaton to make a charged attack. On a hit, it deals additional damage equal to your spark die + your Intelligence modifier.
Scout. (13th level) Your automaton can see in normal or magical darkness up to a range of 120 feet, and it have advantage on all Dexterity (Stealth) checks. Also, it can take the Hide action as a bonus action. Finally, you can see trough its senses and command it at long distances, as if it was a familiar conjured by the find familiar spell.
Energy Absorption. (17th level) Choose one damage type of the following: fire, cold, lighting, radiant, thunder. When the automaton take damage from the chosen type, it regains an amount of hit point equal to the damage taken.
Energy Cannon. (17th level) Choose one damage type: cold, fire, lightning, radiant or thunder. You can spend 4 spark points to cause your automaton to fire a blast of the chosen type, forcing all creatures in a 15-foot radius to make a Dexterity saving throw against your spark save DC, or take 7d6 damage.

You’ve developed the skills necessary to hold your own in close-quarters grappling. You gain the following benefits:
You have advantage on attack rolls against a creature you are grappling.
You can use your action to try to pin a creature grappled by you. To do so, make another grapple check. If you succeed, you and the creature are both restrained until the grapple ends.

(Military Grade) M14, K-bar Knife, Exo-Suit, Dungeoneer's Pack (12 gp). Includes a backpack, a crowbar, a hammer, 10 pitons, 10 torches, a tinderbox, 10 days of rations, and a waterskin. The pack also has 50 feet of hempen rope strapped to the side of it.
Traveler's clothes, an ink pen, a one ounce bottle of ink, a book (perhaps a journal or note book), proof of your position in a military (a letter, insignia, medal, etc.), and a pouch containing 15 gold pieces.

I fight in the name of my country, nothing else matters to me

Justice. Laws are there to keep us safe. I uphold the laws. (Lawful)

My family writes to me every so often. It's good to hear from them.

I fail to understand civilians. What motivates them? What drives them forward?