Mannequins sit between warforged and androids in the gamut of synthetic life in my homebrew. Mannequins are human-like creatures but they are not as perfect as true androids.
YOU WERE MADE, NOT BORN.
Simulation of a living creature is implicit in your shape, though sometimes you forget to boot up your “pretend to breathe” subroutine. But are you a living being who has machine parts, or a machine who has living parts?
Appearance: Your metallic body parts draw attention before people notice one of your eyes is a flickering LED.
Fast Processor. You gain +2 Intelligence.
Skill Bonus. You gain proficiency in Intelligence saving throws.
Built to Last. You have advantage on Constitution saving throws.
Machine Powered. You do not need to eat, drink, or breathe.
Manikin Critical. When you score a critical hit, the attack deals 1d10 extra weapon damage, and you have advantage on to hit rolls against them until the end of the encounter.
MANIKIN RACIAL FEATS
Racial feats have different levels based on the number of ability improvements invested. Any synthetic life – like androids and warforged – may take these feats. You gain the following benefits per investment:
When you get a hand on an enemy, your grip tightens like a steel-jawed vise.
Any time you successfully hit a target with a melee attack that is within 5 feet it must make a Strength saving throw with a DC of 8 + your proficiency bonus + your Strength bonus or become immobilised until the start of your next turn. If you move to a Square that isn’t adjacent to the target, the immobilization ends.
BE MY BATTERY
You transform energy attacks into reserve energy you use to protect and repair yourself
When you take electricity, fire, radiant, or radiation damage you may use your reaction to gain immunity to the triggering damage type until the start of your next turn. You also gain temporary hit points equal to 10 + your Intelligence modifier. This ability recharges after a short or long rest.
DARK ENERGY MELTDOWN
You ‘ve learned to harness the radioactive leakage from your power plant containment vessel to harm your foes.
As an action, you create a burst of radioactive energy out to 10 feet. Each creature in that burst must make a Constitution saving throw or take 2d10 + Intelligence modifier + your level in radiation damage and the target is slowed until the start of your next turn. The DC for this saving throw is 8 + your proficiency bonus + your Intelligence modifier. If the target succeeds on the save it takes half damage but is still slowed.