When determining your character’s ability scores, increase one score by 2 and increase a different score by 1, or increase three different scores by 1. Follow this rule regardless of the method you use to determine the scores, such as rolling or point buy. The “Quick Build” section for your character’s class offers suggestions on which scores to increase. You can follow those suggestions or ignore them, but you can’t raise any of your scores above 20.

Ambyostomas mature to adulthood in 10 years, but have been known to live up to 500 years

Most Ambyostomas are lawful, having been raised in a strict caste system. They tend toward evil as well, coming from a culture where social advancement occurs rarely, and most often because another member of your army has died and there is no one else of that caste to fill the vacancy.

You are Medium

Your base walking speed is 25 feet, and you have a swimming speed of 40 feet.

You can breathe air and water.

Your childish features are an innate part of you. You have learn to use it, at least most of the time…

You have proficiency in the Persuasion skill. 
You have disadvantage on Charisma (Deception) checks and Charisma (Intimidation) checks that rely on sight.

Your skin produce some mucus that make you difficult to restrain.

You have advantage on saving throws against the Restrained or Grappled condition and on checks to end these conditions.

You are used to live in water, clear or muddy. 
You have Darkvision with a range of 60 feet. 

When you are fully immerge in water your gills help you feel your environnement. 
You have Tremorsense with a range of 60 feet and [Tooltip Not Found] with a range of 30 feet.

You also know the Shape Water cantrip. Wisdom is your spellcasting ability for it.

Your metabolism is a piece of art.

As a bonus action, you can expand Hit Die to regain Hit Points, not only during a short or long rest.
You can expend a maximum of Hit Dice equal to your proficiency bonus per bonus action.
You regain expanded Hit Dice when you take a long rest.

You can regrow missing limbs and non-vital organs.
For each missing parts of yourself (organ or limb), you can expend a Hit Die and get a level of exhaustion, then roll the Hit Die + a D20 test against a Constitution check DC 16.

If you are missing some vital parts of your body, like your heart, brain or even your head, you are not considered dead.
Roll your death saving throws as usual, and if your are stable, you can roll a Constitution Check DC 18.
As long as you don’t succeed in the check, you are Incapacitated.
When you suceed, you start your turn with 1 HP and get 5 level of exhaustion . 

If you fail to immerse yourself in water for at least 1 hour during a day, you suffer one level of exhaustion at the end of that day. You can only recover from this exhaustion through magic or by immersing yourself in water for at least 1 hour.