G-Corp War Hero

"The augmentation… I don’t regret it. One downside, though… is that I won’t ever be able to return to civilian life."

The Soldiers of G-Corp were augmented with bug genes to provide an advantage in the War of Smoke. After the war, though, they were abandoned by G-Corp.
You are a special case, given a different, much more expensive augment with things that the lead researcher called 'Gifts'.

Forced Survival - Level 3

"Oh, this arm? I’m proud of it. It’s a tremendous boon to be able to enter the fray of battle… rather than helplessly watch from afar."

G-Corp Augment; Roach
When you take this subclass, an arm of your choice becomes an Augment Roach Arm. This replaces the arm, reducing the weight you can Push, Drag, and Lift by half. You also have disadvantage on checks or saves that would require 2 arms.
The Arm has the Special, Light, and Finesse properties. You are proficient with the Arm.
Due to your arm, your Unarmed strikes using the arm deal 2d6 + (your proficiency bonus) slashing damage instead of their normal damage, and you may choose to change the damage type to Piercing or Bludgeoning damage before each attack as the arm shifts forms slightly.
You cannot Wield a shield due to the arm, however, the Arm itself functions as a shield, providing a +2 bonus to AC.
At level 7, The Arm becomes Magical for the purposes of bypassing resistances and immunities, and gains a +1 to attack and damage rolls, the AC bonus also increases to +3.
At level 10, The Arm gains a +2 to attack and damage rolls instead, and the base damage of the arm changes to 2d8.
At level 15, The Arm gains a +3 to attack and damage rolls instead, and the AC bonus increases to +4.
At level 18, The Arm's AC bonus increases to +5.

Gene Code G-0
At the start of your turn, you heal hit points equal to twice your Proficiency bonus.

G-Corp Corporal - Level 7

"Nowadays… I try not to think much about what I do. It’s getting too taxing to keep up with this otherwise."

Dismember
On a critical hit, roll a d4. The creature you hit has the body part indicated by the d4 dismembered until the end of your next turn, or they receive magical healing of 2nd level or higher:
1. Dismembered Arm; The afflicted creature takes 2d4 damage whenever they make an attack or cast a spell with somatic components. Attack rolls made by the creature have disadvantage.
2. Dismembered Leg; The afflicted creature's movement speed is halved. If the creature is afflicted with Dismembered Leg again, they become prone and cannot stand up until the end of your next turn.
3. Disfigured Face; The afflicted creature has their charisma (Persuasion) modifier fixed to -5 for the duration, but their intimidation modifier increases by 2. The creature also becomes blinded for the duration.
4. Ruptured Torso; The afflicted creature becomes vulnerable to Piercing and Slashing damage, and they have disadvantage on constitution saving throws.

Eviscerate
Once per turn, when you hit a prone creature, the attack becomes a critical hit, and you can choose which Dismemberment effect the creature is afflicted with.
When you reduce a creature to 0 hit points, you heal hit points equal to your Fighter Level. If the attack was a critical hit, you heal twice as much.

The First Wrapping - Level 10

"Suddenly, One Day, My Arm Had... Changed"

Suddenly, One Day
You can cause a Temporary Mutation to your Arm.
As an action, you can cause your arm to temporarily mutate and swing it forward. Make an unarmed strike against a creature within 15 feet of you. On a hit, the creature takes 3 instances of damage from your Arm, and the creature is moved 20 feet away from you and becomes prone.
After using this feature, you cannot use it again until you land a critical hit.

Uncontrolled Morph
Your critical hit range increases to 19-20 for your unarmed strikes.
At the start of your turn, if you are below a quarter of your hit points, you heal equal to your fighter level, and your AC increases by 2 until the start of your next turn.

A Wing's Decisive Weapon - Level 15

"S-stay away... from me..."
"What was that? I can't hear what you're saying, insect!"
"... Oh..."
"Hearken to our darkling wingbeats... as we make our nests in the shadows."
"Oh... mother****er... It's real... The worst one out of the four..."
"You had to hatch now... of all times...?"

Ungeziefer Kaiser
March. March. Consume. Procreate. Consume. Erase. Erase. Regenerate. March.
Extreme Physical Trauma from a Near-Death experience causes your arm to unwrap its first Gift.
When you drop to 0 hit points, you instead heal to full hit points and mutate into The Roach Emperor. The Mutation lasts until you become unconscious, or until 2 hours pass.
This can only trigger once per day.
When you become The Roach Emperor, make a d20 test. If the result is below a 10, you cannot tell friend from foe for the duration, lashing out indiscriminately.
 - If you are immune to Psychic damage, or immune to the Frightened condition, you only lash out when rolling a 5 or less.

When you transform into The Roach Emperor, all of your equipment merges into your form and their effects are disabled.
While you are The Roach Emperor, your AC equals 10 + your constitution modifier + your proficiency bonus.

While you are The Roach Emperor, your size becomes Large, or one size larger if you were already Large or Larger.
When you become The Roach Emperor, you gain 10 stacks of Protecting Pests. While you have Protecting Pests, your Temporary Hit Points are set to (Protecting Pests x Your Fighter Level) at the start of each of your turns. You lose 1 stack of Protecting Pests when you are hit with an attack, or are inflicted with a condition. You lose all stacks of Protecting Pests when you exit The Roach Emperor form.

While you are The Roach Emperor, when you make an attack, choose one of the following attacks to make. Each attack can be made a number of times per turn included in the attack description. If no amount is included, it is assumed to have no limit. All Roach Emperor attacks use your G-Corp Augment Arm for calculating your Attack Roll bonuses.
While you are The Roach Emperor, whenever you land a Critical Hit, you always choose what dismemberment effect happens.
Roach Emperor attacks:

- The Emperor's Fist
Intrude. Infest.
10 foot range, 3d10 + (Your Proficiency Bonus + Protecting Pests) Bludgeoning damage. On a hit, you inflict 1 stack of Hurting Pests to the hit creature.

- The Emperor's Whip
Intrude. Infest. Thrive.
20 foot range, 2d10 + (Your Proficiency Bonus + Protecting Pests) Slashing damage. On a hit, the creature must make a DC (8 + Proficiency Bonus + Protecting Pests) strength saving throw, becoming Prone on a failure.

- March of Roaches
Scour every corner, swarm every height, and take flight.
Ranged Attack (40/80), 3d6 + (Your Proficiency Bonus + Protecting Pests) Bludgeoning damage. On a hit, you inflict 3 stacks of Hurting Pests to the hit creature. This can be used up to twice per turn.

- The Emperor's Devouring
Chaotic, oblivious... Consumption.
10 foot range, 4d12 + (Your Proficiency Bonus + Protecting Pests) Piercing damage. On a hit, consume all of the target's Hurting Pests stacks, and you heal hit points equal to your fighter level for each stack of Hurting Pests consumed. This can be used up to once per turn.

The Emperor's Subjects
When a creature has Hurting Pests stacks, at the start of that creature's turn, they take 1d6 force damage for each stack of Hurting Pests. If a creature with Hurting Pests has Temporary Hit Points, their Temporary Hit Points are reduced by 10 for each stack of Hurting Pests. Hurting Pests has a maximum stack of 10. All stacks of Hurting Pests are removed at the end of combat.
When you reduce a creature to 0 hit points, your Protecting Pests stacks are reset to 10.

The Emperor's Wrath - Level 18

"Are there really no more wrappings underneath...?"

The Emperor's Mantle
You gain 20 Protecting Pests when entering your Roach Emperor form instead of 10. If you have more than 10 Protecting Pests, reducing a creature to 0 hit points does not set your Protecting Pests to 10.
While in the Roach Emperor form, you gain access to new attacks:

- The Emperor's Flogging
I hear it. The abominable, skittering echo outside the window.
30 foot Cone, 3d12 + (your proficiency bonus + protecting pests) Slashing damage. On a hit, inflict 2 Hurting Pests. This can be used once per turn.

- The Emperor's Excision
All that stands in the way... shall be ground to dust.
30 foot range, 4d12 + (your proficiency bonus + protecting pests) Bludgeoning damage. On a hit, if the creature has access to Legendary or Mythic Actions, the damage becomes Critical, and the creature is inflicted with 3 Hurting Pests. This can be used once per turn.

- The Emperor's Feast
Feast. Indulgence.
20 foot range, 4d10 + (your proficiency bonus + protecting pests) Piercing damage. On a hit, if the target has Temporary Hit Points, remove all of their Temporary Hit Points and the damage becomes Critical.

Son, Don't Forget To Go For The Heart
"I Cut Apples in half."
"Some were hard, some crumbly, some were soft, some sappy."
"That Sweet Smell Makes Me..."

When you enter your Roach Emperor form, after you roll for if you attack indiscriminately, you can choose to attempt to 'Cut an Apple'. When you use this feature, select a creature within 40 feet of you and make an attack against them. On a hit, if the creature is not an Ooze, Plant, Aberration, Undead, or a Construct, You pierce their heart with your arm, killing the Creature instantly. If the creature is an Ooze, Plant, Aberration, Undead, or a Construct, you deal 6d12 + (your proficiency bonus + your fighter level) Piercing damage instead.
If you miss this attack, you take 4d6 psychic damage, and you gain only 10 Protecting Pests from The Emperor's Mantle instead of 20.